9.6 ACOS — Arccosine function

Description:

ACOS(X) computes the arccosine of X (inverse of COS(X)).

Standard:

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

Class:

Elemental function

Syntax:

RESULT = ACOS(X)

Arguments:

X	The type shall either be REAL with a magnitude that is less than or equal to one - or the type shall be COMPLEX.

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 \Re \acos(x) \leq \pi.

Example:

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

Specific names:

Name	Argument	Return type	Standard
ACOS(X)	REAL(4) X	REAL(4)	Fortran 77 and later
DACOS(X)	REAL(8) X	REAL(8)	Fortran 77 and later

See also:

Inverse function: COS Degrees function: ACOSD