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# scipy.special.cosm1

scipy.special.cosm1(x, out=None) = <ufunc 'cosm1'>

  cos(x) - 1 for use when x is near zero.

  Parameters:
    xarray_like

      Real valued argument.

    outndarray, optional

      Optional output array for the function results.

  Returns:
    scalar or ndarray

      Values of `cos(x) - 1`.

  See also

  `expm1`, `log1p`

  Examples

      >>> import numpy as np
      >>> import scipy.special as sc

  It is more accurate than computing `cos(x) - 1` directly for `x` around 0.

      >>> x = 1e-30
      >>> np.cos(x) - 1
      0.0
      >>> sc.cosm1(x)
      -5.0000000000000005e-61