nlcpy.expm1

nlcpy.expm1 = <ufunc 'nlcpy_expm1'>

Computes exp(x) - 1 for all elements in the array.

Parameters

xarray_like

Input an array or a scalar.

outndarray or None, optional

A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.

wherearray_like, optional

This condition is broadcast over the input. At locations where the condition is True, the out array will be set to the ufunc result. Elsewhere, the out array will retain its original value. Note that if an uninitialized out array is created via the default out=None, locations within it where the condition is False will remain uninitialized.

**kwargs

For other keyword-only arguments, see the section Optional Keyword Arguments.

Returns

yndarray

A ndarray, containing the exponential minus one: y = exp(x) - 1. If x is a scalar, this function returns the result as a 0-dimension ndarray.

See also

log1p

Computes the element-wise natural logarithm of 1 + x.

Note

This function provides greater precision than exp(x) - 1 for small values of x.

Restriction

• dtype is a complex dtype : TypeError occurs.

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.

>>> import nlcpy as vp
>>> vp.set_printoptions(16) # change displying digits
>>> vp.expm1(1e-10)
array(1.00000000005e-10)
>>> vp.exp(1e-10) - 1
array(1.000000082740371e-10)