huschi.net

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
       attributes(7).
       +-------------------------------+---------------+---------+
       |Interface                      | Attribute     | Value   |
       +-------------------------------+---------------+---------+
       |cacosh(), cacoshf(), cacoshl() | Thread safety | MT-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;
           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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                                  2015-04-19                         CACOSH(3)