Name

cacos, cacosf, cacosl — complex arc cosine

Synopsis

#include <complex.h>
double complex cacos( double complex z);
 
float complex cacosf( float complex z);
 
long double complex cacosl( long double complex z);
 
[Note] Note

Link with −lm.

DESCRIPTION

The cacos() function calculates the complex arc cosine of z. If y = cacos(z), then z = ccos(y). The real part of y is chosen in the interval [0,pi].

One has:

    cacos(z) = −i * clog(z + i * csqrt(1 − z * z))

VERSIONS

These functions first appeared in glibc in version 2.1.

CONFORMING TO

C99.

EXAMPLE

/* Link with "−lm" */

#include <complex.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>

int
main(int argc, char *argv[])
{
    double complex z, c, f;
    double complex i = I;

    if (argc != 3) {
        fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    z = atof(argv[1]) + atof(argv[2]) * I;

    c = cacos(z);

    printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c));

    f = −i * clog(z + i * csqrt(1 − z * z));

    printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f));

    exit(EXIT_SUCCESS);
}

SEE ALSO

ccos(3), clog(3), complex(7)

COLOPHON

This page is part of release 3.52 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man−pages/.


  Copyright 2002 Walter Harms (walter.harmsinformatik.uni-oldenburg.de)
and Copyright (C) 2011 Michael Kerrisk <mtk.manpagesgamil.com>

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