Is there any way to define a matrix in sage that has variables in place for the dimensions?
For instance, I want M with dimension n by p. I try the code below to illustrate
sage: var('n p')
sage: matrix(nrows=n,ncols=p)
This is not shiny but works
var('n p')
n = 2
p = 5
vars1 = [var('a_%d%d' %(i,j)) for i in [1..n] for j in [1..p]]
matrix(SR, n, p, vars1)adapt for n, p > 9
Nope. After :
sage: var("n, p")
(n, p)the Python variable n is indeed bound to a symbolic variable (element of SR) :
sage: n.parent()
Symbolic RingBut after :
sage: n=2 ; p=5n is bound to an integer :
sage: n.parent()
Integer Ringand the rest of your code uses the fixed, integer values of n (and p).
There is currently no way to define a symbolic-dimensioned matrix in Sage (and, unless I'm mistaken (which is possible...), neither in Sympy, Mathematica, Giac or Fricas...).
Asked: 2 years ago
Seen: 267 times
Last updated: Jul 28 '22
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What sort of things do you want to do with these matrices? Maybe there are other options.
One idea is to do matrix manipulations knowing a common dimension. For instance, if I have an M matrix that is n x n, then one idea is to be able to do matrix manipulation that is available for square matrices (i.e. eigenvalue analysis, inversion, etc.)