Ask Your Question
0

exponential matrix exp(A)

asked 2012-03-08 09:51:07 +0100

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

What is the maximum size of a square matrix A to calculate exp(A)

edit retag flag offensive close merge delete

2 Answers

Sort by ยป oldest newest most voted
0

answered 2012-03-08 11:58:25 +0100

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

I don't think there are any hard-coded size limits.

edit flag offensive delete link more
0

answered 2012-03-08 13:30:35 +0100

this post is marked as community wiki

This post is a wiki. Anyone with karma >750 is welcome to improve it.

At the same time, experimentation with random_matrix(ZZ,i,i) suggests that Maxima hits a wall with this already when i=4. RR doesn't look much better, and

sage: m = random_matrix(RDF,4,4)
sage: m.exp?

basically says as much. But

sage: m = random_matrix(RDF,4,4)
sage: exp(m)
[ 0.360479628838 -0.145794589097    1.4781378783  0.316593839994]
[ 0.317770329736 0.0984841855079 -0.733966866354 -0.820812967827]
[ -1.58402218787  0.783288361066  0.965206766202  0.919221986577]
[-0.254553742946  0.837705408602  -2.47262343564   1.63085510321]
sage: m = random_matrix(RDF,10,10)
sage: exp(m)

looks much better. So the answer to your question depends on what you are exactly looking for.

edit flag offensive delete link more

Comments

Indeed, using RDF or CDF will probably scale *much* better.

Jason Grout gravatar imageJason Grout ( 2012-03-10 09:59:31 +0100 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools

Stats

Asked: 2012-03-08 09:51:07 +0100

Seen: 2,338 times

Last updated: Mar 08 '12