Debye frequency: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
en>AnomieBOT
m Bypassing 2 Google redirection URLs. Errors? User:AnomieBOT/shutoff/ReplaceExternalLinks4
 
en>Addbot
m Bot: Migrating 3 interwiki links, now provided by Wikidata on d:q845319
 
Line 1: Line 1:
The name of the writer is Figures but it's not the most masucline title out there. Doing ceramics is what adore doing. Hiring is her day occupation now and she will not change it anytime quickly. Minnesota is where he's been living for many years.<br><br>Check out my site :: [http://spermdonorinfo.co.uk/groups/eliminate-a-yeast-infection-with-one-of-these-tips/ at home std test]
In [[numerical linear algebra]], the '''Jacobi eigenvalue algorithm''' is an [[iterative method]] for the calculation of the [[eigenvalue]]s and [[eigenvector]]s of a [[real number|real]] [[symmetric matrix]]. It is named after [[Carl Gustav Jacob Jacobi]], who first proposed the method in 1846,<ref>{{cite journal
|last=Jacobi |first=C.G.J. |authorlink=Carl Gustav Jacob Jacobi
|url=http://resolver.sub.uni-goettingen.de/purl/?GDZPPN002144522
|title=Über ein leichtes Verfahren, die in der Theorie der Säkularstörungen vorkommenden Gleichungen numerisch aufzulösen
|journal=[[Crelle's Journal]]
|volume=30 |year=1846 |pages=51–94
|language=German
}}</ref> but only became widely used in the 1950s with the advent of computers.<ref>{{cite journal
|first=G.H. |last=Golub
|first2=H.A. |last2=van der Vorst
|title=Eigenvalue computation in the 20th century
|journal=Journal of Computational and Applied Mathematics
|volume=123 |issue=1-2 |year=2000 |pages=35&ndash;65
|doi=10.1016/S0377-0427(00)00413-1
}}</ref>
 
== Description ==
Let ''S'' be a symmetric matrix, and ''G''&nbsp;=&nbsp;''G''(''i'',''j'',''&theta;'') be a [[Givens rotation|Givens rotation matrix]]. Then:
 
:<math>S'=G S G^\top \, </math>
 
is symmetric and [[similar (linear algebra)|similar]] to ''S''.
 
Furthermore, ''S&prime;'' has entries:
 
:<math>\begin{align}
S'_{ii} &= c^2\, S_{ii}  -  2\, s c \,S_{ij}  +  s^2\, S_{jj} \\
S'_{jj} &= s^2 \,S_{ii}  +  2 s c\, S_{ij}  +  c^2 \, S_{jj} \\
S'_{ij} &= S'_{ji} = (c^2 - s^2 ) \, S_{ij}  +  s c \, (S_{ii} - S_{jj} ) \\
S'_{ik} &= S'_{ki} = c \, S_{ik}  -  s \, S_{jk} & k \ne i,j \\
S'_{jk} &= S'_{kj} = s \, S_{ik}  + c \, S_{jk} & k \ne i,j \\
S'_{kl} &= S_{kl} &k,l \ne i,j
\end{align}</math>
 
where ''s''&nbsp;=&nbsp;sin(''&theta;'') and ''c''&nbsp;=&nbsp;cos(''&theta;'').
 
Since ''G'' is orthogonal, ''S'' and ''S''&prime; have the same [[Frobenius norm]] ||·||<sub>F</sub> (the square-root sum of squares of all components), however we can choose ''&theta;'' such that ''S''&prime;<sub>''ij''</sub>&nbsp;=&nbsp;0, in which case ''S''&prime; has a larger sum of squares on the diagonal:
 
:<math> S'_{ij} = \cos(2\theta) S_{ij} + \tfrac{1}{2} \sin(2\theta) (S_{ii} - S_{jj}) </math>
 
Set this equal to 0, and rearrange:
 
:<math> \tan(2\theta) = \frac{2 S_{ij}}{S_{jj} - S_{ii}} </math>
 
if <math>  S_{jj} = S_{ii} </math>
 
:<math> \theta = \frac{\pi} {4}  </math>
 
In order to optimize this effect, ''S''<sub>''ij''</sub> should be the largest off-diagonal component, called the ''pivot''.
 
The Jacobi eigenvalue method repeatedly performs rotations until the matrix becomes almost diagonal. Then the elements in the diagonal are approximations of the (real) eigenvalues of ''S''.
 
== Convergence ==
 
If  <math> p = S_{kl} </math>  is a pivot element, then by definition  <math> |S_{ij} | \le |p| </math>  for  <math> 1 \le i, j \le n, i \ne j</math> . Since ''S '' has exactly  2'' N '':= ''n ''( ''n '' - 1)  off-diag elements, we have  <math>  p^2 \le \Gamma(S )^2 \le 2 N p^2 </math>  or <math>  2 p^2 \ge \Gamma(S )^2 / N </math> .  This implies
<math>  \Gamma(S^J )^2  \le  (1 - 1 / N ) \Gamma (S )^2  </math>  or  <math>  \Gamma (S^ J )  \le (1 - 1 / N )^{1 / 2} \Gamma(S ) </math>,
i.e. the sequence of Jacobi rotations converges at least linearly by a factor  <math>  (1 - 1 / N )^{1 / 2} </math>  to a diagonal matrix.
 
A number of ''N '' Jacobi rotations is called a sweep; let <math> S^{\sigma} </math> denote the result. The previous estimate yields
: <math>  \Gamma(S^{\sigma} )  \le  (1 - 1 / N )^{N / 2} \Gamma(S )  </math>,
i.e. the sequence of sweeps converges at least linearly with a factor  ≈ <math>  e ^{1 / 2}</math> .
 
However the following result of [[Arnold Schönhage|Schönhage]]<ref>{{cite journal
|last=Schönhage |first=A.
|title=Zur quadratischen Konvergenz des Jacobi-Verfahrens
|journal=Numerische Mathematik
|volume=6 |issue=1 |year=1964 |pages=410–412
|language=German
|doi=10.1007/BF01386091 |mr=174171
}}</ref> yields locally quadratic convergence. To this end let ''S'' have ''m'' distinct eigenvalues  <math>  \lambda_1, ... , \lambda_m </math>  with multiplicities  <math>  \nu_1, ... , \nu_m </math>  and let  ''d'' > 0 be the smallest distance of two different eigenvalues. Let us call a number of
 
: <math>  N_S := \frac{1}{2} n (n - 1) - \sum_{\mu = 1}^{m} \frac{1}{2} \nu_{\mu} (\nu_{\mu} - 1) \le N  </math>
 
Jacobi rotations a Schönhage-sweep. If  <math> S^ s </math>  denotes the result then
: <math>  \Gamma(S^ s ) \le\sqrt{\frac{n}{2} - 1} \frac{\gamma^2}{d - 2\gamma}, \quad \gamma :=  \Gamma(S )  </math>  .
 
Thus convergence becomes quadratic as soon as  <math> \Gamma(S ) < d / (2 + \sqrt{\frac{n}{2} - 1}) </math>
 
== Cost ==
 
Each Jacobi rotation can be done in ''n'' steps when the pivot element ''p'' is known. However the search for ''p'' requires inspection of all ''N''&nbsp;≈&nbsp;½&nbsp;''n''<sup>2</sup> off-diag elements. We can reduce this to ''n'' steps too if we introduce an additional index array  <math> m_1, \, \dots \, , \, m_{n - 1} </math>  with the property that <math> m_i </math>  is the index of the largest element in row ''i'', (''i'' = 1, …, ''n''&nbsp;&minus;&nbsp;1) of the current ''S''. Then  (''k'', ''l'')  must be one of the pairs <math>  (i, m_i) </math> . Since only columns ''k'' and ''l'' change, only <math>  m_k \mbox{ and } m_l </math> must be updated, which again can be done in ''n'' steps. Thus each rotation has  O(''n'') cost and one sweep has  O(''n''<sup>3</sup>) cost which is equivalent to one matrix multiplication. Additionally the  <math> m_i </math>  must be initialized before the process starts, this can be done in ''n''<sup>2</sup> steps.
 
Typically the Jacobi method converges within numerical precision after a small number of sweeps. Note that multiple eigenvalues reduce the number of iterations since <math>N_S < N</math>.
 
== Algorithm ==
 
The following algorithm is a description of the Jacobi method in math-like notation.
It calculates a vector ''e'' which contains the eigenvalues and a matrix ''E'' which contains the corresponding eigenvectors, i.e. <math> e_i </math>  is an eigenvalue and the column <math> E_i </math>  an orthonormal eigenvector for <math> e_i </math>,  ''i'' = 1, …, ''n''.
 
'''procedure''' jacobi(''S'' ∈ '''R'''<sup>''n''×''n''</sup>; '''out''' ''e'' ∈ '''R'''<sup>''n''</sup>; '''out''' ''E'' ∈ '''R'''<sup>''n''×''n''</sup>)
  '''var'''
    ''i'', ''k'', ''l'', ''m'', ''state'' ∈ '''N'''
    ''s'', ''c'', ''t'', ''p'', ''y'' ∈ '''R'''
    ''ind'' ∈ '''N'''<sup>''n''</sup>
    ''changed'' ∈ '''L'''<sup>''n''</sup>
  '''function''' maxind(''k'' ∈ '''N''') ∈ '''N''' ! ''index of largest off-diagonal element in row k''
    ''m'' := ''k''+1
    '''for''' ''i'' := ''k''+2 '''to''' ''n'' '''do'''
      '''if''' │''S''<sub>''ki''</sub>│ > │''S''<sub>''km''</sub>│ '''then''' ''m'' := ''i'' '''endif'''
    '''endfor'''
    '''return''' ''m''
  '''endfunc'''
  '''procedure''' update(''k'' ∈ '''N'''; ''t'' ∈ '''R''') ! ''update e<sub>k</sub> and its status''
    ''y'' := ''e''<sub>''k''</sub>; ''e''<sub>''k''</sub> := ''y''+''t''
    '''if''' ''changed''<sub>''k''</sub> and (''y''=''e''<sub>''k''</sub>) '''then''' ''changed''<sub>''k''</sub> := false; ''state'' := ''state''−1
    '''elsif''' (not ''changed''<sub>''k''</sub>) and (''y''≠''e''<sub>''k''</sub>) '''then''' ''changed''<sub>''k''</sub> := true; ''state'' := ''state''+1
    '''endif'''
  '''endproc'''
  '''procedure''' rotate(''k'',''l'',''i'',''j'' ∈ '''N''') ! ''perform rotation of S<sub>ij</sub>, S<sub>kl</sub>''
    ┌ <sub>  </sub>┐    ┌    ┐┌ <sub>  </sub>┐
    │''S''<sub>''kl''</sub>│    │''c''  −''s''││''S''<sub>''kl''</sub>│
    │ <sub>  </sub>│ := │    ││ <sub>  </sub>│
    │''S''<sub>''ij''</sub>│    │''s''  ''c''││''S''<sub>''ij''</sub>│
    └ <sub>  </sub>┘    └    ┘└ <sub>  </sub>┘
  '''endproc'''
  ! ''init e, E, and arrays ind, changed''
  ''E'' := ''I''; ''state'' := ''n''
  '''for''' ''k'' := 1 '''to''' ''n'' '''do''' ''ind''<sub>''k''</sub> := maxind(''k''); ''e''<sub>''k''</sub> := ''S''<sub>''kk''</sub>; ''changed''<sub>''k''</sub> := true '''endfor'''
  '''while''' ''state''≠0 '''do''' ! ''next rotation''
    ''m'' := 1 ! ''find index (k,l) of pivot p''
    '''for''' ''k'' := 2 '''to''' ''n''−1 '''do'''
      '''if''' │''S''<sub>''k''&nbsp;''ind''</sub><sub><sub>''k''</sub></sub>│ > │''S''<sub>''m''&nbsp;''ind''</sub><sub><sub>''m''</sub></sub>│ '''then''' ''m'' := ''k'' '''endif'''
    '''endfor'''
    ''k'' := ''m''; ''l'' := ''ind''<sub>''m''</sub>; ''p'' := ''S''<sub>''kl''</sub>
    ! ''calculate c = cos &phi;, s = sin &phi;''
    ''y'' := (''e''<sub>''l''</sub>−''e''<sub>''k''</sub>)/2; ''t'' := │''y''│+√(''p''<sup>2</sup>+''y''<sup>2</sup>)
    ''s'' := √(''p''<sup>2</sup>+''t''<sup>2</sup>); ''c'' := ''t''/''s''; ''s'' := ''p''/''s''; ''t'' := ''p''<sup>2</sup>/''t''
    '''if''' ''y''<0 '''then''' ''s'' := −''s''; ''t'' := −''t'' '''endif'''
    ''S''<sub>''kl''</sub> := 0.0; update(''k'',−''t''); update(''l'',''t'')
    ! ''rotate rows and columns k and l
    '''for''' ''i'' := 1 '''to''' ''k''−1 '''do''' rotate(''i'',''k'',''i'',''l'') '''endfor'''
    '''for''' ''i'' := ''k''+1 '''to''' ''l''−1 '''do''' rotate(''k'',''i'',''i'',''l'') '''endfor'''
    '''for''' ''i'' := ''l''+1 '''to''' ''n'' '''do''' rotate(''k'',''i'',''l'',''i'') '''endfor'''
    ! ''rotate eigenvectors''
    '''for''' ''i'' := 1 '''to''' ''n'' '''do'''
      ┌ <sub>  </sub>┐    ┌    ┐┌ <sub>  </sub>┐
      │''E''<sub>''ki''</sub>│    │''c''  −''s''││''E''<sub>''ki''</sub>│
      │ <sub>  </sub>│ := │    ││ <sub>  </sub>│
      │''E''<sub>''li''</sub>│    │''s''  ''c''││''E''<sub>''li''</sub>│
      └ <sub>  </sub>┘    └    ┘└ <sub>  </sub>┘
    '''endfor'''
    ! ''rows k, l have changed, update rows ind<sub>k</sub>, ind<sub>l</sub>''
    ''ind''<sub>''k''</sub> := maxind(''k''); ''ind''<sub>''l''</sub> := maxind(''l'')
  '''loop'''
'''endproc'''
 
=== Notes ===
 
1. The logical array ''changed'' holds the status of each eigenvalue. If the numerical value of <math> e_k </math>  or <math> e_l </math>  changes during an iteration, the corresponding component of  ''changed'' is set to ''true'', otherwise to ''false''. The integer ''state''  counts the number of components of ''changed'' which have the value ''true''. Iteration stops as soon as ''state'' = 0. This means that none of the approximations <math> e_1,\, ...\, , e_n </math>  has recently changed its value and thus it is not very likely that this will happen if iteration continues. Here it is assumed that floating point operations are optimally rounded to the nearest floating point number.
 
2. The upper triangle of the matrix ''S'' is destroyed while the lower triangle and the diagonal are unchanged. Thus it is possible to restore ''S'' if necessary according to
 
'''for''' ''k'' := 1 '''to''' ''n''−1 '''do''' ! ''restore matrix S''
  '''for''' ''l'' := ''k''+1 '''to''' ''n'' '''do''' ''S''<sub>''kl''</sub> := ''S''<sub>''lk''</sub> '''endfor'''
'''endfor'''
 
3. The eigenvalues are not necessarily in descending order. This can be achieved by a simple sorting algorithm.
 
'''for''' ''k'' := 1 '''to''' ''n''−1 '''do'''
  ''m'' := ''k''
  '''for''' ''l'' := ''k''+1 '''to''' ''n'' '''do'''
    '''if''' ''e''<sub>''l''</sub> > ''e''<sub>''m''</sub> '''then''' ''m'' := ''l'' '''endif'''
  '''endfor'''
  '''if''' ''k'' ≠ ''m'' '''then''' swap ''e''<sub>''m''</sub>,''e''<sub>''k''</sub>; swap ''E''<sub>''m''</sub>,''E''<sub>''k''</sub> '''endif'''
'''endfor'''
 
4. The algorithm is written using matrix notation (1 based arrays instead of 0 based).
 
5. When implementing the algorithm, the part specified using matrix notation must be performed simultaneously.
 
6. This implementation does not correctly account for the case in which one dimension is an independent subspace.  For example, if given a diagonal matrix, the above implementation will never terminate, as none of the eigenvalues will change.  Hence, in real implementations, extra logic must be added to account for this case.
 
=== Example ===
 
Let
<math>
S = \begin{pmatrix}0.58464 & 0.0505 & 0.6289 & 0.2652 & 0.6857 \\ 0.0505 & 0.19659 & 0.2204 & 0.3552 & 0.0088 \\ 0.6289 & 0.2204 & 0.44907 & 0.1831 & 0.5086 \\ 0.2652 & 0.3552 & 0.1831 & 0.21333 & 0.272 \\ 0.6857 & 0.0088 & 0.5086 & 0.272 & 0.49667  \end{pmatrix}
</math>
 
Then ''jacobi'' produces the following eigenvalues and eigenvectors after 3 sweeps (19 iterations) :
 
<math>
e_1 = 2585.25381092892231
</math>
 
<math>
E_1 = \begin{pmatrix}0.0291933231647860588\\ -0.328712055763188997\\ 0.791411145833126331\\ -0.514552749997152907\end{pmatrix}
</math>
 
<math>
e_2 = 37.1014913651276582
</math>
 
<math>
E_2 = \begin{pmatrix}-0.179186290535454826\\ 0.741917790628453435\\ -0.100228136947192199\\ -0.638282528193614892\end{pmatrix}
</math>
 
<math>
e_3 = 1.4780548447781369
</math>
 
<math>
E_3 = \begin{pmatrix}-0.582075699497237650\\ 0.370502185067093058\\ 0.509578634501799626\\ 0.514048272222164294\end{pmatrix}
</math>
 
<math>
e_4 = 0.1666428611718905
</math>
 
<math>
E_4 = \begin{pmatrix}0.792608291163763585\\ 0.451923120901599794\\ 0.322416398581824992\\ 0.252161169688241933\end{pmatrix}
</math>
 
This link clarifies the example:  
http://www.scribd.com/doc/24953275/Jacobi-Transformation-Used-for-Eigenproblems-for-Symmetric-Matrix
 
== Applications for real symmetric matrices ==
 
When the eigenvalues (and eigenvectors) of a symmetric matrix are known, the following
values are easily calculated.
 
;Singular values
:The singular values of a (square) matrix ''A'' are the square roots of the (non-negative) eigenvalues of <math> A^T A </math>. In case of a symmetric matrix ''S'' we have of <math> S^T S = S^2 </math>, hence the singular values of ''S'' are the absolute values of the eigenvalues of ''S''
 
;2-norm and spectral radius
:The 2-norm of a matrix ''A'' is the norm based on the Euclidean vectornorm, i.e. the largest value <math> \| A x\|_2 </math> when x runs through all vectors with <math> \|x\|_2 = 1 </math>. It is the largest singular value of ''A''. In case of a symmetric matrix it is largest absolute value of its eigenvectors and thus equal to its spectral radius.
 
;Condition number
:The condition number of a nonsingular matrix ''A'' is defined as  <math> \mbox{cond} (A) = \| A \|_2 \| A^{-1}\|_2 </math>. In case of a symmetric matrix it is the absolute value of the quotient of the largest and smallest eigenvalue. Matrices with large condition numbers can cause numerically unstable results: small perturbation can result in large errors. [[Hilbert matrix|Hilbert matrices]] are the most famous ill-conditioned matrices. For example, the fourth-order Hilbert matrix has a condition of 15514, while for order 8 it is 2.7&nbsp;&times;&nbsp;10<sup>8</sup>.
 
;Rank
:A matrix ''A'' has rank ''r'' if it has ''r'' columns that are linearly independent while the remaining columns are linearly dependent on these. Equivalently, ''r'' is the dimension of the range of&nbsp;''A''. Furthermore it is the number of nonzero singular values.
:In case of a symmetric matrix r is the number of nonzero eigenvalues. Unfortunately because of rounding errors numerical approximations of zero eigenvalues may not be zero (it may also happen that a numerical approximation is zero while the true value is not). Thus one can only calculate the ''numerical'' rank by making a decision which of the eigenvalues are close enough to zero.
 
;Pseudo-inverse
:The pseudo inverse of a matrix ''A'' is the unique matrix <math> X = A^+ </math> for which ''AX'' and ''XA'' are symmetric and for which ''AXA = A,  XAX = X''  holds. If ''A'' is nonsingular, then '<math> A^+ = A^{-1} </math>.
:When procedure jacobi (S, e, E) is called, then the relation <math> S = E^T \mbox{Diag} (e) E </math> holds where Diag(''e'')  denotes the diagonal matrix with vector ''e'' on the diagonal. Let <math> e^+ </math> denote the vector where  <math> e_i </math> is replaced by <math> 1/e_i </math> if  <math> e_i \le 0 </math> and by 0  if  <math> e_i </math> is (numerically close to) zero. Since matrix ''E'' is orthogonal, it follows that the pseudo-inverse of S is given by  <math> S^+ = E^T \mbox{Diag} (e^+) E </math>.
 
;Least squares solution
:If matrix ''A''  does not have full rank, there may not be a solution of the linear system  ''Ax = b''. However one can look for a vector x for which  <math> \| Ax - b \|_2 </math> is minimal. The solution is <math> x = A^+ b </math>. In case of a symmetric matrix ''S'' as before, one has <math> x = S^+ b = E^T \mbox{Diag} (e^+) E b </math>.
 
;Matrix exponential
:From <math> S = E^T \mbox{Diag} (e) E </math> one finds <math> \exp S = E^T \mbox{Diag} (\exp e) E </math> where  exp&nbsp;''e''  is the vector where <math> e_i </math> is replaced by <math> exp e_i </math>. In the same way, ''f''(''S'')  can be calculated in an obvious way for any (analytic) function ''f''.
 
;Linear differential equations
:The differential equation  ''x'&nbsp;'' =&nbsp;''Ax'', ''x''(0) = ''a'' has the solution  ''x''(''t'') = exp(''t&nbsp;A'')&nbsp;''a''. For a symmetric matrix ''S'', it follows that  <math> x(t) = E^T \mbox{Diag} (\exp t e) E a </math>. If  <math> a = \sum_{i = 1}^n a_i E_i </math> is the expansion of ''a''  by the eigenvectors of ''S'', then <math> x(t) = \sum_{i = 1}^n a_i \exp(t e_i) E_i </math>.
:Let  <math> W^s </math> be the vector space spanned by the eigenvectors of ''S'' which correspond to a negative eigenvalue and <math> W^u </math> analogously for the positive eigenvalues. If  <math> a \in W^s </math> then <math> \mbox{lim}_{t \ \infty} x(t) = 0 </math> i.e. the equilibrium point 0 is attractive to ''x''(''t''). If <math> a \in W^u </math> then <math> \mbox{lim}_{t \ \infty} x(t) = \infty </math>, i.e. 0 is repulsive to  ''x''(''t''). <math> W^s </math> and <math> W^u </math> are called ''stable'' and ''unstable'' manifolds for ''S''. If ''a'' has components in both manifolds, then one component is attracted and one component is repelled. Hence ''x''(''t'') approaches <math> W^u </math> as <math> t \ \infty </math>.
 
==  Generalizations  ==
 
The Jacobi Method has been generalized to [[Jacobi method for complex Hermitian matrices|complex Hermitian matrices]], general nonsymmetric real and complex matrices as well as block matrices.
 
Since singular values of a real matrix are the square roots of the eigenvalues of the symmetric matrix <math> S = A^T A</math> it can also be used for the calculation of these values. For this case, the method is modified in such a way that ''S'' must not be explicitly calculated which reduces the danger of [[round-off error]]s. Note that <math> J S J^T = J A^T A J^T = J A^T J^T J A J^T = B^T B  </math>  with  <math> B \, := J A J^T </math> .
 
The Jacobi Method is also well suited for parallelism.
 
==  References  ==
{{reflist}}
 
== Further reading ==
{{refbegin}}
*{{Citation | last1=Press | first1=WH | last2=Teukolsky | first2=SA | last3=Vetterling | first3=WT | last4=Flannery | first4=BP | year=2007 | title=Numerical Recipes: The Art of Scientific Computing | edition=3rd | publisher=Cambridge University Press |  publication-place=New York | isbn=978-0-521-88068-8 | chapter=Section 11.1. Jacobi Transformations of a Symmetric Matrix | chapter-url=http://apps.nrbook.com/empanel/index.html#pg=570}}
* {{cite journal
|last=Rutishauser |first=H.
|title=Handbook Series Linear Algebra: The Jacobi method for real symmetric matrices.
|journal=Numerische Mathematik
|volume=9 |issue=1 |year=1966 |pages=1–10
|doi=10.1007/BF02165223 |mr=1553948
}}
* {{cite journal
|last=Sameh |first=A.H.
|title=On Jacobi and Jacobi-like algorithms for a parallel computer
|journal=[[Mathematics of Computation]]
|volume=25 |issue=115 |year=1971 |pages=579–590
|mr=297131 | jstor = 2005221
}}
* {{cite journal
|last=Shroff |first=Gautam M.
|title=A parallel algorithm for the eigenvalues and eigenvectors of a general complex matrix
|journal=Numerische Mathematik
|volume=58 |issue=1 |year=1991 |pages=779–805
|doi=10.1007/BF01385654 |mr=1098865
}}
* {{cite journal
|last=Veselić |first=K.
|title=On a class of Jacobi-like procedures for diagonalising arbitrary real matrices
|journal=Numerische Mathematik
|volume=33 |issue=2 |year=1979 |pages=157–172
|doi=10.1007/BF01399551 |mr=549446
}}
* {{cite journal
|last=Veselić |first=K.
|last2=Wenzel |first2=H. J.
|title=A quadratically convergent Jacobi-like method for real matrices with complex eigenvalues
|journal=Numerische Mathematik
|volume=33 |issue=4 |year=1979 |pages=425–435
|doi=10.1007/BF01399324 |mr=553351
}}
 
{{refend}}
 
== External links ==
*[http://www.maths.lancs.ac.uk/~gilbert/m306c/node17.html Jacobi's Method]
*[http://math.fullerton.edu/mathews/n2003/JacobiMethodMod.html Jacobi Iteration for Eigenvectors]
*[http://groups.google.com/group/sci.math.num-analysis/msg/8282d0d412f72d2e Matlab implementation of Jacobi algorithm that avoids trigonometric functions]
 
{{Numerical linear algebra}}
 
[[Category:Numerical linear algebra]]
[[Category:Articles with example pseudocode]]

Latest revision as of 01:13, 7 March 2013

In numerical linear algebra, the Jacobi eigenvalue algorithm is an iterative method for the calculation of the eigenvalues and eigenvectors of a real symmetric matrix. It is named after Carl Gustav Jacob Jacobi, who first proposed the method in 1846,[1] but only became widely used in the 1950s with the advent of computers.[2]

Description

Let S be a symmetric matrix, and G = G(i,j,θ) be a Givens rotation matrix. Then:

S=GSG

is symmetric and similar to S.

Furthermore, S′ has entries:

S'ii=c2Sii2scSij+s2SjjS'jj=s2Sii+2scSij+c2SjjS'ij=S'ji=(c2s2)Sij+sc(SiiSjj)S'ik=S'ki=cSiksSjkki,jS'jk=S'kj=sSik+cSjkki,jS'kl=Sklk,li,j

where s = sin(θ) and c = cos(θ).

Since G is orthogonal, S and S′ have the same Frobenius norm ||·||F (the square-root sum of squares of all components), however we can choose θ such that Sij = 0, in which case S′ has a larger sum of squares on the diagonal:

S'ij=cos(2θ)Sij+12sin(2θ)(SiiSjj)

Set this equal to 0, and rearrange:

tan(2θ)=2SijSjjSii

if Sjj=Sii

θ=π4

In order to optimize this effect, Sij should be the largest off-diagonal component, called the pivot.

The Jacobi eigenvalue method repeatedly performs rotations until the matrix becomes almost diagonal. Then the elements in the diagonal are approximations of the (real) eigenvalues of S.

Convergence

If p=Skl is a pivot element, then by definition |Sij||p| for 1i,jn,ij . Since S has exactly 2 N := n ( n - 1) off-diag elements, we have p2Γ(S)22Np2 or 2p2Γ(S)2/N . This implies Γ(SJ)2(11/N)Γ(S)2 or Γ(SJ)(11/N)1/2Γ(S), i.e. the sequence of Jacobi rotations converges at least linearly by a factor (11/N)1/2 to a diagonal matrix.

A number of N Jacobi rotations is called a sweep; let Sσ denote the result. The previous estimate yields

Γ(Sσ)(11/N)N/2Γ(S),

i.e. the sequence of sweeps converges at least linearly with a factor ≈ e1/2 .

However the following result of Schönhage[3] yields locally quadratic convergence. To this end let S have m distinct eigenvalues λ1,...,λm with multiplicities ν1,...,νm and let d > 0 be the smallest distance of two different eigenvalues. Let us call a number of

NS:=12n(n1)μ=1m12νμ(νμ1)N

Jacobi rotations a Schönhage-sweep. If Ss denotes the result then

Γ(Ss)n21γ2d2γ,γ:=Γ(S) .

Thus convergence becomes quadratic as soon as Γ(S)<d/(2+n21)

Cost

Each Jacobi rotation can be done in n steps when the pivot element p is known. However the search for p requires inspection of all N ≈ ½ n2 off-diag elements. We can reduce this to n steps too if we introduce an additional index array m1,,mn1 with the property that mi is the index of the largest element in row i, (i = 1, …, n − 1) of the current S. Then (k, l) must be one of the pairs (i,mi) . Since only columns k and l change, only mk and ml must be updated, which again can be done in n steps. Thus each rotation has O(n) cost and one sweep has O(n3) cost which is equivalent to one matrix multiplication. Additionally the mi must be initialized before the process starts, this can be done in n2 steps.

Typically the Jacobi method converges within numerical precision after a small number of sweeps. Note that multiple eigenvalues reduce the number of iterations since NS<N.

Algorithm

The following algorithm is a description of the Jacobi method in math-like notation. It calculates a vector e which contains the eigenvalues and a matrix E which contains the corresponding eigenvectors, i.e. ei is an eigenvalue and the column Ei an orthonormal eigenvector for ei, i = 1, …, n.

procedure jacobi(SRn×n; out eRn; out ERn×n)
  var
    i, k, l, m, stateN
    s, c, t, p, yR
    indNn
    changedLn

  function maxind(kN) ∈ N ! index of largest off-diagonal element in row k
    m := k+1
    for i := k+2 to n do
      ifSki│ > │Skmthen m := i endif
    endfor
    return m
  endfunc

  procedure update(kN; tR) ! update ek and its status
    y := ek; ek := y+t
    if changedk and (y=ek) then changedk := false; state := state−1
    elsif (not changedk) and (yek) then changedk := true; state := state+1
    endif
  endproc

  procedure rotate(k,l,i,jN) ! perform rotation of Sij, Skl  ┐    ┌     ┐┌   ┐
    │Skl│    │cs││Skl│
    │   │ := │     ││   │
    │Sij│    │s   c││Sij│
    └   ┘    └     ┘└   endproc

  ! init e, E, and arrays ind, changed
  E := I; state := n
  for k := 1 to n do indk := maxind(k); ek := Skk; changedk := true endfor
  while state≠0 do ! next rotation
    m := 1 ! find index (k,l) of pivot p
    for k := 2 to n−1 do
      ifSk indk│ > │Sm indmthen m := k endif
    endfor
    k := m; l := indm; p := Skl
    ! calculate c = cos φ, s = sin φ
    y := (elek)/2; t := │y│+√(p2+y2)
    s := √(p2+t2); c := t/s; s := p/s; t := p2/t
    if y<0 then s := −s; t := −t endif
    Skl := 0.0; update(k,−t); update(l,t)
    ! rotate rows and columns k and l
    for i := 1 to k−1 do rotate(i,k,i,l) endfor
    for i := k+1 to l−1 do rotate(k,i,i,l) endfor
    for i := l+1 to n do rotate(k,i,l,i) endfor
    ! rotate eigenvectors
    for i := 1 to n do  ┐    ┌     ┐┌   ┐
      │Eki│    │cs││Eki│
      │   │ := │     ││   │
      │Eli│    │s   c││Eli│
      └   ┘    └     ┘└   endfor
    ! rows k, l have changed, update rows indk, indl
    indk := maxind(k); indl := maxind(l)
  loop
endproc

Notes

1. The logical array changed holds the status of each eigenvalue. If the numerical value of ek or el changes during an iteration, the corresponding component of changed is set to true, otherwise to false. The integer state counts the number of components of changed which have the value true. Iteration stops as soon as state = 0. This means that none of the approximations e1,...,en has recently changed its value and thus it is not very likely that this will happen if iteration continues. Here it is assumed that floating point operations are optimally rounded to the nearest floating point number.

2. The upper triangle of the matrix S is destroyed while the lower triangle and the diagonal are unchanged. Thus it is possible to restore S if necessary according to

for k := 1 to n−1 do ! restore matrix S
  for l := k+1 to n do Skl := Slk endfor
endfor

3. The eigenvalues are not necessarily in descending order. This can be achieved by a simple sorting algorithm.

for k := 1 to n−1 do
  m := k
  for l := k+1 to n do
    if el > em then m := l endif
  endfor
  if km then swap em,ek; swap Em,Ek endif
endfor

4. The algorithm is written using matrix notation (1 based arrays instead of 0 based).

5. When implementing the algorithm, the part specified using matrix notation must be performed simultaneously.

6. This implementation does not correctly account for the case in which one dimension is an independent subspace. For example, if given a diagonal matrix, the above implementation will never terminate, as none of the eigenvalues will change. Hence, in real implementations, extra logic must be added to account for this case.

Example

Let S=(0.584640.05050.62890.26520.68570.05050.196590.22040.35520.00880.62890.22040.449070.18310.50860.26520.35520.18310.213330.2720.68570.00880.50860.2720.49667)

Then jacobi produces the following eigenvalues and eigenvectors after 3 sweeps (19 iterations) :

e1=2585.25381092892231

E1=(0.02919332316478605880.3287120557631889970.7914111458331263310.514552749997152907)

e2=37.1014913651276582

E2=(0.1791862905354548260.7419177906284534350.1002281369471921990.638282528193614892)

e3=1.4780548447781369

E3=(0.5820756994972376500.3705021850670930580.5095786345017996260.514048272222164294)

e4=0.1666428611718905

E4=(0.7926082911637635850.4519231209015997940.3224163985818249920.252161169688241933)

This link clarifies the example: http://www.scribd.com/doc/24953275/Jacobi-Transformation-Used-for-Eigenproblems-for-Symmetric-Matrix

Applications for real symmetric matrices

When the eigenvalues (and eigenvectors) of a symmetric matrix are known, the following values are easily calculated.

Singular values
The singular values of a (square) matrix A are the square roots of the (non-negative) eigenvalues of ATA. In case of a symmetric matrix S we have of STS=S2, hence the singular values of S are the absolute values of the eigenvalues of S
2-norm and spectral radius
The 2-norm of a matrix A is the norm based on the Euclidean vectornorm, i.e. the largest value Ax2 when x runs through all vectors with x2=1. It is the largest singular value of A. In case of a symmetric matrix it is largest absolute value of its eigenvectors and thus equal to its spectral radius.
Condition number
The condition number of a nonsingular matrix A is defined as cond(A)=A2A12. In case of a symmetric matrix it is the absolute value of the quotient of the largest and smallest eigenvalue. Matrices with large condition numbers can cause numerically unstable results: small perturbation can result in large errors. Hilbert matrices are the most famous ill-conditioned matrices. For example, the fourth-order Hilbert matrix has a condition of 15514, while for order 8 it is 2.7 × 108.
Rank
A matrix A has rank r if it has r columns that are linearly independent while the remaining columns are linearly dependent on these. Equivalently, r is the dimension of the range of A. Furthermore it is the number of nonzero singular values.
In case of a symmetric matrix r is the number of nonzero eigenvalues. Unfortunately because of rounding errors numerical approximations of zero eigenvalues may not be zero (it may also happen that a numerical approximation is zero while the true value is not). Thus one can only calculate the numerical rank by making a decision which of the eigenvalues are close enough to zero.
Pseudo-inverse
The pseudo inverse of a matrix A is the unique matrix X=A+ for which AX and XA are symmetric and for which AXA = A, XAX = X holds. If A is nonsingular, then 'A+=A1.
When procedure jacobi (S, e, E) is called, then the relation S=ETDiag(e)E holds where Diag(e) denotes the diagonal matrix with vector e on the diagonal. Let e+ denote the vector where ei is replaced by 1/ei if ei0 and by 0 if ei is (numerically close to) zero. Since matrix E is orthogonal, it follows that the pseudo-inverse of S is given by S+=ETDiag(e+)E.
Least squares solution
If matrix A does not have full rank, there may not be a solution of the linear system Ax = b. However one can look for a vector x for which Axb2 is minimal. The solution is x=A+b. In case of a symmetric matrix S as before, one has x=S+b=ETDiag(e+)Eb.
Matrix exponential
From S=ETDiag(e)E one finds expS=ETDiag(expe)E where exp e is the vector where ei is replaced by expei. In the same way, f(S) can be calculated in an obvious way for any (analytic) function f.
Linear differential equations
The differential equation x' Ax, x(0) = a has the solution x(t) = exp(t Aa. For a symmetric matrix S, it follows that x(t)=ETDiag(expte)Ea. If a=i=1naiEi is the expansion of a by the eigenvectors of S, then x(t)=i=1naiexp(tei)Ei.
Let Ws be the vector space spanned by the eigenvectors of S which correspond to a negative eigenvalue and Wu analogously for the positive eigenvalues. If aWs then limtx(t)=0 i.e. the equilibrium point 0 is attractive to x(t). If aWu then limtx(t)=, i.e. 0 is repulsive to x(t). Ws and Wu are called stable and unstable manifolds for S. If a has components in both manifolds, then one component is attracted and one component is repelled. Hence x(t) approaches Wu as t.

Generalizations

The Jacobi Method has been generalized to complex Hermitian matrices, general nonsymmetric real and complex matrices as well as block matrices.

Since singular values of a real matrix are the square roots of the eigenvalues of the symmetric matrix S=ATA it can also be used for the calculation of these values. For this case, the method is modified in such a way that S must not be explicitly calculated which reduces the danger of round-off errors. Note that JSJT=JATAJT=JATJTJAJT=BTB with B:=JAJT .

The Jacobi Method is also well suited for parallelism.

References

43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.

Further reading

Template:Refbegin

  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  • One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang

Template:Refend

External links

Template:Numerical linear algebra

  1. One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  2. One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang
  3. One of the biggest reasons investing in a Singapore new launch is an effective things is as a result of it is doable to be lent massive quantities of money at very low interest rates that you should utilize to purchase it. Then, if property values continue to go up, then you'll get a really high return on funding (ROI). Simply make sure you purchase one of the higher properties, reminiscent of the ones at Fernvale the Riverbank or any Singapore landed property Get Earnings by means of Renting

    In its statement, the singapore property listing - website link, government claimed that the majority citizens buying their first residence won't be hurt by the new measures. Some concessions can even be prolonged to chose teams of consumers, similar to married couples with a minimum of one Singaporean partner who are purchasing their second property so long as they intend to promote their first residential property. Lower the LTV limit on housing loans granted by monetary establishments regulated by MAS from 70% to 60% for property purchasers who are individuals with a number of outstanding housing loans on the time of the brand new housing purchase. Singapore Property Measures - 30 August 2010 The most popular seek for the number of bedrooms in Singapore is 4, followed by 2 and three. Lush Acres EC @ Sengkang

    Discover out more about real estate funding in the area, together with info on international funding incentives and property possession. Many Singaporeans have been investing in property across the causeway in recent years, attracted by comparatively low prices. However, those who need to exit their investments quickly are likely to face significant challenges when trying to sell their property – and could finally be stuck with a property they can't sell. Career improvement programmes, in-house valuation, auctions and administrative help, venture advertising and marketing, skilled talks and traisning are continuously planned for the sales associates to help them obtain better outcomes for his or her shoppers while at Knight Frank Singapore. No change Present Rules

    Extending the tax exemption would help. The exemption, which may be as a lot as $2 million per family, covers individuals who negotiate a principal reduction on their existing mortgage, sell their house short (i.e., for lower than the excellent loans), or take part in a foreclosure course of. An extension of theexemption would seem like a common-sense means to assist stabilize the housing market, but the political turmoil around the fiscal-cliff negotiations means widespread sense could not win out. Home Minority Chief Nancy Pelosi (D-Calif.) believes that the mortgage relief provision will be on the table during the grand-cut price talks, in response to communications director Nadeam Elshami. Buying or promoting of blue mild bulbs is unlawful.

    A vendor's stamp duty has been launched on industrial property for the primary time, at rates ranging from 5 per cent to 15 per cent. The Authorities might be trying to reassure the market that they aren't in opposition to foreigners and PRs investing in Singapore's property market. They imposed these measures because of extenuating components available in the market." The sale of new dual-key EC models will even be restricted to multi-generational households only. The models have two separate entrances, permitting grandparents, for example, to dwell separately. The vendor's stamp obligation takes effect right this moment and applies to industrial property and plots which might be offered inside three years of the date of buy. JLL named Best Performing Property Brand for second year running

    The data offered is for normal info purposes only and isn't supposed to be personalised investment or monetary advice. Motley Fool Singapore contributor Stanley Lim would not personal shares in any corporations talked about. Singapore private home costs increased by 1.eight% within the fourth quarter of 2012, up from 0.6% within the earlier quarter. Resale prices of government-built HDB residences which are usually bought by Singaporeans, elevated by 2.5%, quarter on quarter, the quickest acquire in five quarters. And industrial property, prices are actually double the levels of three years ago. No withholding tax in the event you sell your property. All your local information regarding vital HDB policies, condominium launches, land growth, commercial property and more

    There are various methods to go about discovering the precise property. Some local newspapers (together with the Straits Instances ) have categorised property sections and many local property brokers have websites. Now there are some specifics to consider when buying a 'new launch' rental. Intended use of the unit Every sale begins with 10 p.c low cost for finish of season sale; changes to 20 % discount storewide; follows by additional reduction of fiftyand ends with last discount of 70 % or extra. Typically there is even a warehouse sale or transferring out sale with huge mark-down of costs for stock clearance. Deborah Regulation from Expat Realtor shares her property market update, plus prime rental residences and houses at the moment available to lease Esparina EC @ Sengkang