# Fortran Wiki acos

## Description

acos(x) computes the arccosine of x (inverse of cos(x)).

## Standard

FORTRAN 77 and later, for a complex argument Fortran 2008 and later

## Class

Elemental function

## Styntax

result = acos(x)

## Arguments

• x - The type shall be real with a magnitude that is less than one.

## Return value

The return value is of the same type and kind as x. The real part of the result is in radians and lies in the range $0 \leq \acos(x) \leq \pi$.

## Example

program test_acos
real(8) :: x = 0.866_8
x = acos(x)
end program test_acos