numpy.expm1 — NumPy v1.11 Manual (original) (raw)
numpy.expm1(_x_[, _out_]) = <ufunc 'expm1'>¶
Calculate exp(x) - 1 for all elements in the array.
| Parameters: | x : array_like Input values. |
|---|---|
| Returns: | out : ndarray Element-wise exponential minus one: out = exp(x) - 1. |
See also
log(1 + x), the inverse of expm1.
Notes
This function provides greater precision than exp(x) - 1for small values of x.
Examples
The true value of exp(1e-10) - 1 is 1.00000000005e-10 to about 32 significant digits. This example shows the superiority of expm1 in this case.
np.expm1(1e-10) 1.00000000005e-10 np.exp(1e-10) - 1 1.000000082740371e-10