from brian2 import log)
log(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj])¶
Natural logarithm, element-wise.
The natural logarithm
log()is the inverse of the exponential function, so that
log(exp(x)) = x. The natural logarithm is logarithm in base
x : array_like
out : ndarray, None, or tuple of ndarray and None, optional
A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.
where : array_like, optional
This condition is broadcast over the input. At locations where the condition is True, the
outarray will be set to the ufunc result. Elsewhere, the
outarray will retain its original value. Note that if an uninitialized
outarray is created via the default
out=None, locations within it where the condition is False will remain uninitialized.
For other keyword-only arguments, see the ufunc docs.
y : ndarray
The natural logarithm of
x, element-wise. This is a scalar if
xis a scalar.
Logarithm is a multivalued function: for each
xthere is an infinite number of
exp(z) = x. The convention is to return the
zwhose imaginary part lies in
For real-valued input data types,
log()always returns real output. For each value that cannot be expressed as a real number or infinity, it yields
nanand sets the
invalidfloating point error flag.
For complex-valued input,
log()is a complex analytical function that has a branch cut
[-inf, 0]and is continuous from above on it.
log()handles the floating-point negative zero as an infinitesimal negative number, conforming to the C99 standard.
[R21] M. Abramowitz and I.A. Stegun, “Handbook of Mathematical Functions”, 10th printing, 1964, pp. 67. http://www.math.sfu.ca/~cbm/aands/ [R22] Wikipedia, “Logarithm”. https://en.wikipedia.org/wiki/Logarithm
>>> np.log([1, np.e, np.e**2, 0]) array([ 0., 1., 2., -Inf])