numpy.ldexp — NumPy v1.11 Manual (original) (raw)
numpy.ldexp(x1, _x2_[, _out_]) = <ufunc 'ldexp'>¶
Returns x1 * 2**x2, element-wise.
The mantissas x1 and twos exponents x2 are used to construct floating point numbers x1 * 2**x2.
| Parameters: | x1 : array_like Array of multipliers. x2 : array_like, int Array of twos exponents. out : ndarray, optional Output array for the result. |
|---|---|
| Returns: | y : ndarray or scalar The result of x1 * 2**x2. |
See also
Return (y1, y2) from x = y1 * 2**y2, inverse to ldexp.
Notes
Complex dtypes are not supported, they will raise a TypeError.
ldexp is useful as the inverse of frexp, if used by itself it is more clear to simply use the expression x1 * 2**x2.
Examples
np.ldexp(5, np.arange(4)) array([ 5., 10., 20., 40.], dtype=float32)
x = np.arange(6) np.ldexp(*np.frexp(x)) array([ 0., 1., 2., 3., 4., 5.])