Wednesday, October 17, 2012

GRtensor commands

I would try to collect some useful resources for GRtensor package of Maple.
I contains a host of commands which are very useful but the documentation is scarce.

A good page to learn the applicability of the commands through example is
http://www.smf.mx/~dgfm-smf/TallerVI/CursoSussman/hoja2/hoja21.html

All GRtensor outputs needs o be simplified one way or another and GRtensor provides specialized routines to accomplish just that. The gralter command does the job instead of the Maple command simplify.
http://grtensor.phy.queensu.ca/Griihelp/gralter.help

And everyone needs to know the keyboard shortcuts of any program they are using. It makes life efficient.
http://www.maplesoft.com/support/help/Maple/view.aspx?path=worksheet%2fdocumenting%2f2DMathShortcutKeys

For example, I was unable to enter the Greek symbols for a long time till I found that it is very easy to do so in Maple. Just type the Greek word in English and press escape key. A menu pops up displaying all names that can be entered which begins with the letters entered. Most of the time it is the first entry. So I just start typing lamb ESC and press enter to get the λ symbol.

Substitute:

To calc. with a general form and then substitute the functional form use subs command.

So if I have to calc. the G_ab of a complicated metric which is of the f(r) metric form then I would instead calc. using the f(r) metric and then substitute the functional form of the f(r) .




But this works only for individual components of a tensor which are extracted by the grcomponent command. To apply the substitution on an entire tensor w have to use the grmap command.

grmap:

http://grtensor.phy.queensu.ca/Griihelp/grmap.help




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