acos(x) computes the arccosine of x (inverse of cos(x)).
FORTRAN 77 and later
Elemental function
result = acos(x)
x - The type shall be real with a magnitude that is less than one.The return value is of type real and it lies in the range . The return value if of the same kind as x.
program test_acos
real(8) :: x = 0.866_8
x = acos(x)
end program test_acos
Inverse function: cos