How to take element-wise logarithm of a matrix in sympy?

Question

Working with a sympy Matrix or numpy array of sympy symbols, how does one take the element-wise logarithm?

For example, if I have:

m=sympy.Matrix(sympy.symbols('a b c d'))

Then np.abs(m) works fine, but np.log(m) does not work ("AttributeError: log").

Any solutions?

Answer 1

Use Matrix.applyfunc:

In [6]: M = sympy.Matrix(sympy.symbols('a b c d'))

In [7]: M.applyfunc(sympy.log)
Out[7]:
⎡log(a)⎤
⎢      ⎥
⎢log(b)⎥
⎢      ⎥
⎢log(c)⎥
⎢      ⎥
⎣log(d)⎦

You can't use np.log because that does a numeric log, but you want the symbolic version, i.e., sympy.log.