numpy.signbit

numpy.signbit(x[, out]) = <ufunc 'signbit'>

Returns element-wise True where signbit is set (less than zero).

Parameters:

Parameters:	x : array_like The input value(s). out : ndarray, optional Array into which the output is placed. Its type is preserved and it must be of the right shape to hold the output. See `doc.ufuncs`.
Returns:	result : ndarray of bool Output array, or reference to `out` if that was supplied.

x : array_like

The input value(s).

out : ndarray, optional

Array into which the output is placed. Its type is preserved and it must be of the right shape to hold the output. See doc.ufuncs.

Returns:

result : ndarray of bool

Output array, or reference to out if that was supplied.

>>> np.signbit(-1.2)
True
>>> np.signbit(np.array([1, -2.3, 2.1]))
array([False,  True, False], dtype=bool)