cacosh(3)

CACOSH(3)                  Linux Programmer's Manual                 CACOSH(3)

NAME
       cacosh, cacoshf, cacoshl - complex arc hyperbolic cosine

SYNOPSIS
       #include <complex.h>

       double complex cacosh(double complex z);
       float complex cacoshf(float complex z);
       long double complex cacoshl(long double complex z);

       Link with -lm.

DESCRIPTION
       These  functions  calculate the complex arc hyperbolic cosine of z.  If
       y = cacosh(z), then z = ccosh(y).  The imaginary part of y is chosen in
       the interval [-pi,pi].  The real part of y is chosen nonnegative.

       One has:

           cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z - 1) / 2))

VERSIONS
       These functions first appeared in glibc in version 2.1.

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +-------------------------------+---------------+---------+
       |Interface                      | Attribute     | Value   |
       +-------------------------------+---------------+---------+
       |cacosh(), cacoshf(), cacoshl() | Thread safety | MT-Safe |
       +-------------------------------+---------------+---------+
CONFORMING TO
       C99, POSIX.1-2001, POSIX.1-2008.

EXAMPLES
       /* 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;

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

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

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

           f = 2 * clog(csqrt((z + 1)/2) + csqrt((z - 1)/2));
           printf("formula  = %6.3f %6.3f*i\n", creal(f2), cimag(f2));

           exit(EXIT_SUCCESS);
       }

SEE ALSO
       acosh(3), cabs(3), ccosh(3), cimag(3), complex(7)

COLOPHON
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                                  2020-06-09                         CACOSH(3)