acos(x: array, /) array

Calculates an implementation-dependent approximation of the principal value of the inverse cosine, having domain [-1, +1] and codomain [+0, +π], for each element x_i of the input array x. Each element-wise result is expressed in radians.

Special cases

For floating-point operands,

  • If x_i is NaN, the result is NaN.

  • If x_i is greater than 1, the result is NaN.

  • If x_i is less than -1, the result is NaN.

  • If x_i is 1, the result is +0.


x (array) – input array. Should have a floating-point data type.


out (array) – an array containing the inverse cosine of each element in x. The returned array must have a floating-point data type determined by Type Promotion Rules.