One missing maxima feature, that I have the math behind, but not a program
Subject: One missing maxima feature, that I have the math behind, but not a program
From: Rupert Swarbrick
Date: Sat, 07 Dec 2013 11:16:52 +0000
Mike Valenzuela <mickle.mouse at gmail.com> writes:
> Hello all,
>
> I was recently making use of the matrixexp function, when I realized there
> is a related operation that Maxima does not yet appear to support natively.
>
> matrixexp(A * t) is often useful for solving linear differential equations.
> Similarly, A^^t is useful for solving (discrete) difference equations.
>
> However, I could not find an operation to perform A^^t. So anyways I threw
> together a sample maxima program which carries out a matrix exponential and
> an A^^t by "hand" (it isn't automated). I was wondering if anyone cared to
> convert the A^^t to some method that Maxima can call?
If you have floating point inputs, you might be interested in this
thread:
http://thread.gmane.org/gmane.comp.mathematics.maxima.general/40488
Nothing more came of it at the time, but if we have an unrelated user
maybe I should push harder... :-) We could do something like call this
function in the simplifier if it sees that the entire matrix is formed
of floating point data.
If you want symbolic matrix exponentials, you could try the code in
diag.mac. It works by putting the matrix in Jordan canonical form and
then adding up the (finite) Taylor series.
Rupert
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