log2(x, out=None, **kwargs)

Base-2 logarithm of x.

  • x (ndarray or scalar) – Input values.

  • out (ndarray or None) – A location into which the result is stored. If provided, it must have the same shape and type as the input. If not provided or None, a freshly-allocated array is returned.


  • y (ndarray) – The logarithm base two of x, element-wise. This is a scalar if x is a scalar.

  • .. note:: – This function differs from the original numpy.log2 in the following way(s):

    • only ndarray or scalar is accpted as valid input, tuple of ndarray is not supported

    • broadcasting to out of different shape is currently not supported

    • when input is plain python numerics, the result will not be stored in the out param


>>> x = np.array([0, 1, 2, 2**4])
>>> np.log2(x)
array([-inf,   0.,   1.,   4.])