Lahey/GNU Fortran

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### 8.6 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