The
ACOS function returns the
angle, expressed in radians, whose cosine is *
X*
(i.e., the arc-cosine). The range of ACOS is between 0 and *
p*
.

The cosine of the desired angle in the range (-1 *
<=*
*
X*
*
<=*
1). If *
X*
is double-precision floating, the result of ACOS is also double-precision. *
X*
cannot be complex. All other types are converted to single-precision floating-point and yield floating-point results. If *
X*
is an array, the result has the same structure, with each element containing the
arc-cosine of the corresponding element of *
X*
.