The periodic function COS returns the trigonometric cosine of X.

The angle for which the cosine is desired, specified in radians. If *
X*
is double-precision floating or complex, the result is of the same type. All other types are converted to single-precision floating-point and yield floating-point results. When applied to complex numbers:

COS(*
x*
) = COMPLEX(cos *
I*
cosh *
R*
, -sin *
R*
sinh (*
-I*
))

where *
R*
and *
I*
are the real and imaginary parts of *
x*
.

If *
X*
is an array, the result has the same structure, with each element containing the cosine of the corresponding element of *
X*
.