HP Fortran Programmer's Reference (September 2007)

Intrinsic procedures
Intrinsic procedure specifications
Chapter 11516
ACHAR(IACHAR(C)) must have the value C for any character C capable of representation in the
processor.
ACOS(X)
Description
Arccosine (inverse cosine) function in radians.
Class
Elemental function.
Argument
X must be of type real with a value that satisfies the inequality |X| <= 1.
Result type/
type parameters
Same as X.
Result value
The result has a value equal to a processor-dependent approximation to arccos(X), expressed
in radians. It lies in the range 0 <= ACOS(X) <= Pi.
Specific forms
DCOS, QACOS.
ACOSD(X)
Description
Arccosine (inverse cosine) function in degrees.
Class
Elemental nonstandard function.
Argument
X must be of type real with a value that satisfies the inequality |X| <= 1.