SymPy - substitute sybolic entries in a matrix

Question

I have a python function which generates a sympy.Matrix with symbolic entries. It works effectively like:

import sympy as sp
M = sp.Matrix([[1,0,2],[0,1,2],[1,2,         


        

Answer 1

Given that the answer from Andrew was helpful it seems like you might be interested in the MatrixSymbol.

In [1]: from sympy import *

In [2]: X = MatrixSymbol('X', 3, 4)

In [3]: X  # completely symbolic
Out[3]: X

In [4]: Matrix(X)  # Expand to explicit matrix 
Out[4]: 
⎡X₀₀  X₀₁  X₀₂  X₀₃⎤
⎢                  ⎥
⎢X₁₀  X₁₁  X₁₂  X₁₃⎥
⎢                  ⎥
⎣X₂₀  X₂₁  X₂₂  X₂₃⎦

But answering your original question, perhapcs you could get the symbols out of the matrix that you produce?

x12 = X[1, 2]