acos, acosl

raw OCR

Calculates the arc cosine.

Defined in header <math.h>

Syntax

Real versions:                            Complex version:
#include <math.h>                         #include <complex.h>
double acos(double x);                    complex  acos(complex x);
long double acosKlong double x);

Portability

	DOS	UNIX	Windows	ANSI C	C++ only
acosi	■		■
Real acos	■	■	■	■
Complex acos	■		■		■

Remarks

acos returns the arc cosine of the input value, acosi is the long double version; it takes a long double argument and returns a long double result. Real arguments to acos and acosi must be in the range -1 to 1, or else acos and acosi return NAN and set the global variable errno to

EDOM Domain error

The complex inverse cosine is defined by

acos(z) = -/ log(z + i sqrtd - z^))

Return value

acos and acosi of a real argument between -1 and +1 returns a value in the range 0 to pi.

Error handling for these routines can be modified through the functions matiierr and _matlierri.

Example

#include <stdio.h>
#include <inath.h>

int main(void)
{
   double result, x     .5;

   result = acos(x);
   printfC'The arc cosine of %lf  is %lf\n", x, result)
   return 0;

Differences from modern implementations

Nothing recorded yet.

Modern references

These are search links, not yet checked by hand.

Extraction notes

heading `acos, acosi` read as `acos, acosl`

Stable link: /3.1/math.h/acos/ · short form /3.1/acos/