`numpy.lib.scimath:log`

source: /numpy/lib/_scimath_impl.py :241

Signature

def log ( x )

Summary

Compute the natural logarithm of x.

Extended Summary

Return the "principal value" (for a description of this, see numpy.log) of $l o g_{e} (x)$ . For real x > 0, this is a real number (log(0) returns -inf and log(np.inf) returns inf). Otherwise, the complex principle value is returned.

Parameters

x : array_like: The value(s) whose log is (are) required.

Returns

out : ndarray or scalar: The log of the x value(s). If x was a scalar, so is out, otherwise an array is returned.

Notes

For a log() that returns NAN when real x < 0, use numpy.log (note, however, that otherwise numpy.log and this log are identical, i.e., both return -inf for x = 0, inf for x = inf, and, notably, the complex principle value if x.imag != 0).

Examples

import numpy as np

✓

np.emath.log(np.exp(1))

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Negative arguments are handled "correctly" (recall that ``exp(log(x)) == x`` does *not* hold for real ``x < 0``):

np.emath.log(-np.exp(1)) == (1 + np.pi * 1j)

✗

Aliases

numpy.emath.log