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)

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