CACOS

Section: Linux Programmer's Manual (3)
Updated: 2015-04-19
Index Return to Main Contents
 

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);

Link with -lm.  

DESCRIPTION

These functions calculate 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.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
cacos(), cacosf(), cacosl() Thread safetyMT-Safe
 

CONFORMING TO

C99, POSIX.1-2001, POSIX.1-2008.  

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

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Index

NAME
SYNOPSIS
DESCRIPTION
VERSIONS
ATTRIBUTES
CONFORMING TO
EXAMPLE
SEE ALSO
COLOPHON

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Time: 09:30:03 GMT, September 25, 2018