015i_cacosh.asciidoc

cacosh

NAME

cacosh - 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);

CONFORMING TO

C99

DESCRIPTION

The cacosh() function calculates 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 non-negative.

One has: cacosh(z) = 2 * clog(csqrtz + 1) / 2) + csqrt((z - 1) / 2

RETURN VALUE

Returns the complex arc hyperbolic cosine value in the range of a half-strip of non-negative values along the real axis in the interval [-I*pi,I*pi] along the imaginary axis.

SEE ALSO

acosh, cabs, ccosh, cimag, complex

EXAMPLE

link:src/cacosh.c[role=include]

OUTPUT

$ gcc -Wall -lm cacosh.c
$ ./a.out 1 2
cacosh() =  1.529  1.144*i
formula  =  1.529  1.144*i