# cos function

(Shortest import: `from brian2 import cos)`

brian2.units.unitsafefunctions.cos(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature])

  Cosine element-wise.

  Parameters:

    x : array_like

    > Input array in radians.

    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:

    y : ndarray

    > The corresponding cosine values. This is a scalar if `x` is a scalar.

  Notes

  If `out` is provided, the function writes the result into it, and returns a reference to `out`. (See Examples)

  References

  M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions. New York, NY: Dover, 1972.

  Examples

      >>> import numpy as np
      >>> np.cos(np.array([0, np.pi/2, np.pi]))
      array([  1.00000000e+00,   6.12303177e-17,  -1.00000000e+00])
      >>>
      >>> # Example of providing the optional output parameter
      >>> out1 = np.array([0], dtype='d')
      >>> out2 = np.cos([0.1], out1)
      >>> out2 is out1
      True
      >>>
      >>> # Example of ValueError due to provision of shape mis-matched `out`
      >>> np.cos(np.zeros((3,3)),np.zeros((2,2)))
      Traceback (most recent call last):
        File "<stdin>", line 1, in <module>
      ValueError: operands could not be broadcast together with shapes (3,3) (2,2)