numpy.emath.log#
- emath.log(x)[source]#
Compute the natural logarithm of x.
Return the “principal value” (for a description of this, see
numpy.log
) of \(log_e(x)\). For real x > 0, this is a real number (log(0)
returns-inf
andlog(np.inf)
returnsinf
). Otherwise, the complex principle value is returned.- Parameters:
- xarray_like
The value(s) whose log is (are) required.
- Returns:
- outndarray or scalar
The log of the x value(s). If x was a scalar, so is out, otherwise an array is returned.
See also
Notes
For a log() that returns
NAN
when real x < 0, usenumpy.log
(note, however, that otherwisenumpy.log
and thislog
are identical, i.e., both return-inf
for x = 0,inf
for x = inf, and, notably, the complex principle value ifx.imag != 0
).Examples
>>> np.emath.log(np.exp(1)) 1.0
Negative arguments are handled “correctly” (recall that
exp(log(x)) == x
does not hold for realx < 0
):>>> np.emath.log(-np.exp(1)) == (1 + np.pi * 1j) True