dpnp.arccos¶

dpnp.arccos = <DPNPUnaryFunc 'acos'>¶

Computes inverse cosine for each element \(x_i\) for input array x.

The inverse of dpnp.cos so that, if \(y = cos(x)\), then \(x = acos(y)\). Note that dpnp.arccos is an alias of dpnp.acos.

For full documentation refer to numpy.acos.

Parameters:

x{dpnp.ndarray, usm_ndarray}

Input array, expected to have a floating-point data type.

out{None, dpnp.ndarray, usm_ndarray, tuple of ndarray}, optional

Output array to populate. Array must have the correct shape and the expected data type. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.

Default: None.

order{None, "C", "F", "A", "K"}, optional

Memory layout of the newly output array, if parameter out is None.

Default: "K".

Returns:

outdpnp.ndarray: An array containing the element-wise inverse cosine, in radians and in the closed interval \([0, \pi]\). The data type of the returned array is determined by the Type Promotion Rules.

Limitations

Parameters where and subok are supported with their default values. Keyword argument kwargs is currently unsupported. Otherwise NotImplementedError exception will be raised.

See also

dpnp.cos: Trigonometric cosine, element-wise.
dpnp.atan: Trigonometric inverse tangent, element-wise.
dpnp.asin: Trigonometric inverse sine, element-wise.
dpnp.acosh: Hyperbolic inverse cosine, element-wise.

Notes

dpnp.acos is a multivalued function: for each x there are infinitely many numbers z such that \(cos(z) = x\). The convention is to return the angle z whose the real part lies in the interval \([0, \pi]\).

For real-valued floating-point input data types, dpnp.acos always returns real output. For each value that cannot be expressed as a real number or infinity, it yields NaN.

For complex floating-point input data types, dpnp.acos is a complex analytic function that has, by convention, the branch cuts \((-\infty, -1)\) and \((1, \infty)\) and is continuous from above on the former and from below on the latter.

The inverse cosine is also known as \(cos^{-1}\).

Examples

>>> import dpnp as np
>>> x = np.array([1, -1])
>>> np.acos(x)
array([0.0,  3.14159265])