The ACOS function returns the trigonometric arccosine of a real number, in radians.
Syntax
ACOS (x)
x is an INTENT(IN) scalar or array of type REAL and must be within the range
A REAL representation, expressed in radians, of the arccosine of x.
Example
real :: x=.5 write(*,*) acos(x) ! writes 1.0471975