Software for General Relativity

[Worldline]

What is the best software for GR calculations ? GRTensor ?

 

[bcrowell]

"Best" is going to be subjective, and there is going to be different software for different tasks in GR. But my workhorse is maxima with ctensor. Both maxima and ctensor are free and open source.

 

[pervect]

I like GrTensor a lot better than Maxima. Though I can't swear that it isn't liking what I use. There are a few things to beware of with GrTensor - the built in Christofel symbols are a bit funky (just an index interchange, and you can define your own macro to fix it, but you could get caught easily if you didn't catch it.)

The biggest problem I find is getting things to simplify - the automatic simplification process seems a bit obtuse. It helps to give it "assumptions", which tell it how to make things under a square roo t positive. (It's not good at guessing that, and it matters to the sign of the result).

The latex output from GrTensor sometimes needs some rework when posting it to PF.

It's still incredibly powerful software.

 

[bcrowell]

I like GrTensor a lot better than Maxima.

Unfortunately GrTensor only works with expensive, proprietary computer algebra systems: Maple and Mathematica. An academic single-user license for Maple is $1200. I gave up on Mathematica back in the 90's when an operating system upgrade caused it to stop working on my machine, and Wolfram told me my only option was to buy a new copy.

 

[martinbn]

You can try http://cadabra.phi-sci.com/, it is free.

 

[Worldline]

Thank you for ur comments

 

[bcrowell]

I think cadabra is purely for coordinate-independent calculations.