What software do real physicists use for GR calculations?

[BWV]

for GR calculations?

is there some standard off the shelf software package, or do they do the code themselves?

 

[George Jones]

for GR calculations?

is there some standard off the shelf software package, or do they do the code themselves?

They use various packages, including the Maple package GRTensorII.

 

[LithiumHelios]

I've also seen quite a few Mathematica notebooks dotted around the place. Glancing at Hartle he places some references to such notebooks in his book.

http://www.physics.ucsb.edu/~gravitybook/mathematica.html - Here's the link to his Mathematica programs.

 

[nicksauce]

In my GR class this year we had an assignment to make a program in Maple/Matlab/Mathematica to calculate the Christoffel symbols, Ricci Tensor, Geodesic equations, etc. given any n dimensional metric. Wasn't terribly hard to do.

 

[robphy]

Some still use pencil and paper... for tensorial calculations.

 

[George Jones]

Some still use pencil and paper... for tensorial calculations.

I think that it is important for students to practise pen and paper tensorial calculations, but I think most professionals use computer packages to do calculations that are of any real complexity. For example, the book An Introduction to General relativity and Cosmology by Peblanski and Krasinski states

"Calculating the curvature tensor from a given metric tensor is tedious and time-consuming, and seemingly innocent errors made along the way cause great chaos in the final results. In order to obtain a reliable result, every step of the calculation must be carefully verified. A relatively simple calculation typically takes several hours; in complicated cases it can extend to months...

The modern computer algebra programs are fairly easy to use, and the reduction in time and effort required to do a calculation is dramatic. Instead of doing a routine calculation for weeks, one can have the result in less than a minute. ... these calculation are done 'by hand' essentially only by students for educational purposes. In research work, the computers have taken over the field completely."

 

[skippy1729]

Are there any decent programs (linux preferred) which do not rely on expensive packages e.g. Maple, Mathematica, MatLab?

Skippy

 

[skippy1729]

I found a reference to a program SHEEP on wikipedia but the download link ftp://euclid.maths.qmw.ac.uk/pub/sheep/[/URL] doesn't work. Runs with LISP. Anyone know where to get it?

Skippy

 

[Mentz114]

Maxima, which runs on Linux and Windows is available here. There are interfaces also for Linux and Windows.

maxima.sourceforge.net

It has a package called ctensor which can calculate most of the GR tensors for different observer frames. I've got some batch files for various calculations I could pass along.