How can I take the square root of -1 using python?

Question

When I take the square root of -1 it gives me an error:

invalid value encountered in sqrt

How do I fix that?

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Answer 1

To avoid the invalid value warning/error, the argument to numpy's sqrt function must be complex:

In [8]: import numpy as np

In [9]: np.sqrt(-1+0j)
Out[9]: 1j

As @AshwiniChaudhary pointed out in a comment, you could also use the cmath standard library:

In [10]: cmath.sqrt(-1)
Out[10]: 1j