Python - Inversing complex arrays

Question

I have some square matrix with complex values and want to inverse it.

If I try:

(my_matrix)**(-1)

I get:

ZeroDivisionError: 0.0 to a negative or complex power

If I try:

import numpy as np
np.linalg.inv(my_matrix)

I get:

TypeError: No loop matching the specified signature and casting was found for ufunc inv

How to invert complex Array?

You can't use simply python to work with matrixes. You may use pandas. https://stackoverflow.com/questions/40858835/calculating-the-inverse-of-a-matrix-with-pandas — Vahram Danielyan, May 22 '21 at 22:30
Tell us more about that array. `shape`, `dtype`, and some values (or all if not too large) — hpaulj, May 22 '21 at 23:12
`x**-1` is element wise division, unless `x` is `np.matrix`. — hpaulj, May 22 '21 at 23:27
Apparently `my_matrix` is not a numpy `array` or `matrix`, or if it is, its data type is not a numeric type. What is `type(my_matrix)`? If it is a numpy array or matrix, what is `my_matrix.dtype`? — Warren Weckesser, May 22 '21 at 23:39

score 1 · Answer 1 · answered May 22 '21 at 22:39

1

You can't use strictly python to work on matrixes and analyze arrays. I would recommend using Pandas or Numpy, which are easy-to-use libraries that will be able to solve your problem.

answered May 22 '21 at 22:39

jahantaila

840
5
26

Thought Numpy works, I've used it and it works for me. I think you need to use other libraries if you do it with numpy – jahantaila May 22 '21 at 22:43
So you inversed array with COMPLEX values? – Wiktor Kujawa May 22 '21 at 22:45
Semi-Complex, it will work. I use Jupyter Notebook IDE – jahantaila May 22 '21 at 22:46
I use jupyter too – Wiktor Kujawa May 22 '21 at 22:48
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/232746/discussion-between-boetis-and-wiktor-kujawa). – jahantaila May 22 '21 at 22:49

hpaulj · Answer 2 · 2021-05-23T03:54:44.500

From the sample posted in the discussion (https://chat.stackoverflow.com/rooms/232746/discussion-between-boetis-and-wiktor-kujawa) I was able to recreate a (4,4) complex_dtype array (it took some tedious editing):

In [501]: np.array(my_matrix)
Out[501]: 
array([[-4.90995593-0.0388j    , -0.        -0.j        ,
        -1.21084206-0.9213362j , -0.05935173-0.04516105j],
       [-0.        -0.j        , -4.90995593-0.0388j    ,
        -0.05935173-0.04516105j, -1.21084206-0.9213362j ],
       [-1.21084206+0.9213362j , -0.05935173+0.04516105j,
        -4.90995593-0.0388j    , -0.        -0.j        ],
       [-0.05935173+0.04516105j, -1.21084206+0.9213362j ,
        -0.        -0.j        , -4.90995593-0.0388j    ]])
In [502]: x=_
In [503]: np.linalg.inv(x)
Out[503]: 
array([[-0.22536285+2.16108358e-03j, -0.00234657+6.35524029e-05j,
         0.05633771+4.13312304e-02j,  0.003354  +2.44488004e-03j],
       [-0.00234657+6.35524029e-05j, -0.22536285+2.16108358e-03j,
         0.003354  +2.44488004e-03j,  0.05633771+4.13312304e-02j],
       [ 0.0548569 -4.32773491e-02j,  0.00325069-2.58066414e-03j,
        -0.22536285+2.16108358e-03j, -0.00234657+6.35524029e-05j],
       [ 0.00325069-2.58066414e-03j,  0.0548569 -4.32773491e-02j,
        -0.00234657+6.35524029e-05j, -0.22536285+2.16108358e-03j]])

The scipy.linalg.inv does the same thing.

In [505]: x.dtype
Out[505]: dtype('complex128')
In [506]: x.shape
Out[506]: (4, 4)

with object dtype:

Producing your errors:

In [512]: np.linalg.inv(x.astype(object))
Traceback (most recent call last):
  File "<ipython-input-512-615f0ffc3570>", line 1, in <module>
    np.linalg.inv(x.astype(object))
  File "<__array_function__ internals>", line 5, in inv
  File "/usr/local/lib/python3.8/dist-packages/numpy/linalg/linalg.py", line 545, in inv
    ainv = _umath_linalg.inv(a, signature=signature, extobj=extobj)
TypeError: No loop matching the specified signature and casting was found for ufunc inv

In [513]: x.astype(object)**-1
Traceback (most recent call last):
  File "<ipython-input-513-65fe9688f840>", line 1, in <module>
    x.astype(object)**-1
ZeroDivisionError: 0.0 to a negative or complex power

Python - Inversing complex arrays

2 Answers2

with object dtype: