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HP-UX 11i Version 3: February 2007

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acosd(), acosdf(), acosdl(), acosdw(), acosdq() — degree-valued arccosine functions


#include <math.h>

double acosd(double x);

float acosdf(float x);

HP Integrity Server Only

long double acosdl(long double x);

extended acosdw(extended x);

quad acosdq(quad x);


acosd() returns the degree-valued arccosine of x, in the range 0 to 180.

acosdf() is a float version of acosd(); it takes a float argument and returns a float result.

Integrity Server Only

acosdl() is a long double version of acosd(); it takes a long double argument and returns a long double result.

acosdw() is an extended version of acosd(); it takes an extended argument and returns an extended result.

acosdq() is equivalent to acosdl() on HP-UX systems.


To use these functions, compile either with the default -Ae option or with the -Aa and -D_HPUX_SOURCE options.

To use (for Integrity servers) acosdw() or acosdq(), compile also with the -fpwidetypes option.

To use any of these functions, make sure your program includes <math.h>, and link in the math library by specifying -lm on the compiler or linker command line.

For more information, see the HP-UX floating-point guide for HP Integrity servers at the following site: http://www.hp.com/go/fp.


acosd() returns +0.

If the magnitude of x is greater than one, acosd() returns NaN and raises the invalid exception.

If x is NaN, acosd() returns NaN.


If the magnitude of x is greater than one, acosd() sets errno to [EDOM].

Integrity Server Only

HP-UX libm functions on Integrity server do not set errno by default. For errno setting, compile with the +Olibmerrno option.


These functions are not specified by any standard.

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