# numpy.emath.arccos#

emath.arccos(x)[source]#

Compute the inverse cosine of x.

Return the “principal value” (for a description of this, see numpy.arccos) of the inverse cosine of x. For real x such that abs(x) <= 1, this is a real number in the closed interval $$[0, \pi]$$. Otherwise, the complex principle value is returned.

Parameters:
xarray_like or scalar

The value(s) whose arccos is (are) required.

Returns:
outndarray or scalar

The inverse cosine(s) of the x value(s). If x was a scalar, so is out, otherwise an array object is returned.

Notes

For an arccos() that returns NAN when real x is not in the interval [-1,1], use numpy.arccos.

Examples

>>> np.set_printoptions(precision=4)

>>> np.emath.arccos(1) # a scalar is returned
0.0

>>> np.emath.arccos([1,2])
array([0.-0.j   , 0.-1.317j])