Green's function (many-body theory): Difference between revisions

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{{External links|date=March 2012}}
Hello and welcome. My name is Irwin and I completely dig that title. To collect coins is one of the issues I adore most. Puerto Rico is exactly where he and his spouse reside. For years I've been operating as a payroll clerk.<br><br>Here is my weblog [http://change-university.com/groups/curing-your-yeast-infection-how-to-accomplish-it-easily/ http://change-university.com/groups/curing-your-yeast-infection-how-to-accomplish-it-easily/]
 
{{Islam}}
 
'''Salat times''' refers to times when [[Muslims]] perform prayers (''[[salat]]''). The term is primarily used for the five daily prayers plus the Friday prayer. According to Muslim beliefs, the salat times were taught by [[Allah]] to [[Muhammad]].
 
Prayer times are standard for [[Muslims]] in the world, especially the fard prayer times. They depend on the condition of the [[Sun]] and geography. There are varying opinions regarding the exact salat times, the [[Madh'hab|schools of Islamic thought]] differing in minor details. All schools agree that any given prayer cannot be performed before its stipulated time.
 
==Five daily prayers==
The five daily prayers are obligatory (''[[fard]]'') and they are performed at times determined essentially by the position of the Sun in the sky. Hence, salat times vary at different locations on the Earth. 
* [http://www.islamicity.com/ISLAMITV/?ref=1274 Video about Salat]
* [http://www.islamicity.com/mosque/salat/PRAYER-KATALOG2.pdf Printable Prayer Description]
 
===Fajr (pre-dawn)===
Fajr begins at subh saadiq - true dawn or morning twilight  when the morning light appears across the full width of the sky and ends at sunrise
 
===Dhuhr (midday)===
{{Main|Dhuhr}}
The Dhuhr prayer starts after the sun passes its [zenith], and lasts until Asr
 
===Asr (afternoon)===
{{Main|Asr}}
The Asr prayer starts when the shadow of an object is the same length as the object itself (or, according to [[Hanafi]] fiqh, twice its length) and lasts till sunset.  Asr can be split into two sections; the preferred time is before the sun starts to turn orange, while the time of necessity is from when the sun turns orange until sunset.
 
===Maghrib (sunset)===
{{Main|Maghrib}}
The Maghrib prayer begins when the sun sets, and lasts till the red light has left the sky in the west.
 
===Isha'a (night)===
{{Main|Isha'a}}
The Isha'a prayer starts when the red light is gone from the western sky, and lasts until the rise of the "white light" (fajar sadiq) in the east. The preferred time for Isha'a is before midnight, meaning halfway between sunset and sunrise.
* [http://www.islamicity.com/multimedia/CyberTV/ch17/default.asp?inc=1.htm#Isha_Prayers Video Salat Isha'a] in Makkah and Madinah.
 
== Time calculation ==
[[File:Equation of time.png|thumb|Equation of time]]
[[File:Sun-declination.jpg|thumb|Declination of the sun]]
 
To calculate prayer times two astronomical measures are necessary, the declination of the sun and the difference between clock time and [[sundial clock]]. This difference being the result of the eccentricity of the earth's orbit and the inclination of its axis, it is called the Equation of time. The declination of the sun is the angle between sun's rays and the equator plan.<ref>[http://aa.usno.navy.mil/faq/docs/SunApprox.php Approximate Solar Coordinates]</ref>
 
In addition to the above measures, to calculate prayer times for a specific location we need its spherical coordinates.<ref>[http://praytimes.org/calculation/#Calculating_Prayer_Times Calculating Prayer Times]</ref>
 
In the following <math> T_Z </math> is the time zone, and <math>T_E</math> the time equation value. <math> L </math> and <math> D </math> are respectively the [[Longitude]] and the [[Latitude]] of the considered point.
 
An other important equation gives the time difference between when the sun hits its highest point in the sky (Dhuhr time) and any other angle <math>\alpha</math>, as follow:
<math> T(\alpha) = {1 \over 15} \arccos \left( {-\sin(\alpha)-\sin(L)*\sin(D) \over \cos(L)*\cos(D)} \right) </math>
 
* Midday (Dhuhr) time is easily obtained. When the sun reaches the mid sky, time is given by: <math>T_{Dhuhr} = 12 + T_Z - (L/15 + T_E)</math>
* Sunrise (Chorok) and Sunset (Maghreb) time are given by <math> T(0.833) </math>, in fact it is the astronomical sunset/sunrise that occurs for <math>\alpha = 0 </math>. 0.833 is a slight correction that gives the actual time. So <math>T_{Chorok} = T_{Dhuhr} - T(0.833)</math> and <math>T_{Sunset} = T_{Dhuhr} + T(0.833)</math>.
If we consider the elevation of the point we should add another correction to the constant <math> 0.0347 \times \sqrt{h} </math>.
* For Fajr and Isha many conventions about the angle <math>\alpha</math> exist. It is of 17 and 18 degrees respectively for Fadjr and Isha prayers according to the [[Muslim World League]].
* For Asr time according to the majority of Muslim schools, including [[Shafi'i]], [[Maliki]], [[Ja'fari]], and [[Hanbali]], it is when the length of an object shadows became equal to its length plus the length of its shadow at noon. The Hanafi schools states that the time of Asr is when an object's shadow reaches two times the length of the object itself, plus the length of its shadow at noon. The time the shadow of an object reaches <math>T</math> times its length is given by the equation: <math>A(T) =  {1 \over 15} \arccos \left( {\sin(\arccot(t+\tan(L-D)))-\sin(L)*\sin(D) \over \cos(L)*\cos(D)} \right)</math>.
* It is called for the Maghrib prayer when the sun is completely folded behind the horizon, plus 3 minutes by precaution.
 
{{clear}}
 
==Friday prayer==
{{Main|Jumu'ah}}
The Friday prayer replaces the dhuhr prayer performed on the other six days of the week. The precise time for this congregational prayer varies with the mosque, but in all cases it must be performed after the dhuhr and before the asr times. If one is unable to join the congregation, then they must pray the dhuhr prayer instead. This
salat is compulsory to be done with ja'maat for men. Women have the option to perform Jumm'ah in the mosque or to pray dhuhr
* [http://www.islamicity.com/multimedia/CyberTV/ch17/default.asp?inc=1.htm#Friday_(Jumuah)_Prayers Video Salat Jumah/Friday] in Makkah and Madinah.
 
==Other salat==
 
===Eid prayers===
Eid-ul-Adhaa and Eid-ul-Fitr
{{Main|Salat al Eid}}
* [http://www.islamicity.com/multimedia/CyberTV/ch17/default.asp?inc=1.htm#Eid-ul_Fitr_Prayers Video Salat Eid-ul-Fitr] in Makkah and Madinah.
* [http://www.islamicity.com/multimedia/CyberTV/ch18/default.asp?inc=1.htm#Salat Video Salat Eid-ul-Adhaa] in Makkah and Madinah.
 
===Taraweeh===
Salat during Ramadhan, performed at night after Isha (night) prayer. Usually performed in congregation.
* [http://www.islamicity.com/multimedia/CyberTV/ch17/default.asp?inc=8.htm#Taraweeh_Prayer_1429 Video Salat Taraweeh] in Makkah and Madinah, Ramadan 1429 AH or 2008 AC.
 
===Janaaza===
Salat at a funeral
 
==References==
 
{{reflist}}
* [http://ig.internetplus.biz/prayertimes/en- Prayer times] for many countries
* [http://www.prayertimes.info Prayer Times] Prayer times are calculated based location of the IP address.
* [http://www.islamicfinder.org/world.php Prayer Times] for more than 6 million cities in 252 countries in the world.
* [http://www.islamicity.com/prayertimes Printable Prayer Times] for more than 3.7 million cities in 200 countries in the world as well as latitude and longitude inputs.
*[http://reminder.salaahtimes.co.za Salaah Time Reminders on Twitter for various Cities in South Africa]
*[http://www.al-islam.org/encyclopedia/chapter7/6.html Salat according to some Islamic schools of thought]
 
{{Islamic prayer}}
 
[[Category:Salat]]
[[Category:Islam stubs]]

Latest revision as of 20:54, 24 November 2014

Hello and welcome. My name is Irwin and I completely dig that title. To collect coins is one of the issues I adore most. Puerto Rico is exactly where he and his spouse reside. For years I've been operating as a payroll clerk.

Here is my weblog http://change-university.com/groups/curing-your-yeast-infection-how-to-accomplish-it-easily/