# numpy.expm1

numpy.expm1(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj]) = <ufunc 'expm1'>

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

  Parameters
    x array_like

      Input values.

    out ndarray, None, or tuple of ndarray and 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.

    where array_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 ufunc docs.

  Returns
    out ndarray or scalar

      Element-wise exponential minus one: `out = exp(x) - 1`. This is a scalar if x is a scalar.

  See also

  `log1p`

    `log(1 + x)`, the inverse of expm1.

  Notes

  This function provides greater precision than `exp(x) - 1` for 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

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