Imaginary Matrices in Sympy using MatrixSymbol

Question

Multiplying a matrix with the imaginary unit raises an exception, ie,

import sympy as sy 

M = sy.MatrixSymbol('M', 2, 2)  
print(sy.I * M)

raises the exception

TypeError: Invalid comparison of non-real I

My current workaround is to replace sy.I with an i = sy.Symbol('i') . Is there a better way to use the MatrxixSymbol together with imaginary expressions? Thanks.

PS: Conda Python 3.7.6 and Sympy version 1.5.1 is used.

Answer 1

This is a bug in SymPy. I've opened github.com/sympy/sympy/issues/18743 for it. The bug only occurs when printing the expression, so you can work around it by avoiding printing the expression.