mxnet.np.log¶
-
log
(x, out=None, **kwargs)¶ 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 e.
- Parameters
x (ndarray) – Input value. Elements must be of real value.
out (ndarray or None, optional) – A location into which the result is stored. If provided, it must have the same shape and dtype as input ndarray. If not provided or None, a freshly-allocated array is returned.
- Returns
y (ndarray) – The natural logarithm of x, element-wise. This is a scalar if x is a scalar.
.. note:: – Currently only supports data of real values and
inf
as input. Returns data of real value,inf
,-inf
andnan
according to the input. This function differs from the original numpy.log in the following aspects:Does not support complex number for now
Input type does not support Python native iterables(list, tuple, …).
out
param: cannot perform auto broadcasting.out
ndarray’s shape must be the same as the expected output.out
param: cannot perform auto type cast.out
ndarray’s dtype must be the same as the expected output.out
param does not support scalar input case.
Examples
>>> a = np.array([1, np.exp(1), np.exp(2), 0], dtype=np.float64) >>> np.log(a) array([ 0., 1., 2., -inf], dtype=float64) >>> # Using the default float32 dtype leads to slightly different behavior >>> a = np.array([1, np.exp(1), np.exp(2), 0]) >>> np.log(a) array([ 0., 0.99999994, 2., -inf]) >>> np.log(1) 0.0