.\" Copyright 2002 Walter Harms(walter.harms@informatik.uni-oldenburg.de) .\" and Copyright (C) 2011 Michael Kerrisk .\" Distributed under GPL .\" .TH CACOSH 3 2011-09-15 "" "Linux Programmer's Manual" .SH NAME cacosh, cacoshf, cacoshl \- complex arc hyperbolic cosine .SH SYNOPSIS .B #include .sp .BI "double complex cacosh(double complex " z ); .br .BI "float complex cacoshf(float complex " z ); .br .BI "long double complex cacoshl(long double complex " z ); .sp Link with \fI\-lm\fP. .SH DESCRIPTION The .BR cacosh () function calculates the complex arc hyperpolic cosine of .IR z . If \fIy\ =\ cacosh(z)\fP, then \fIz\ =\ ccosh(y)\fP. The imaginary part of .I y is chosen in the interval [\-pi,pi]. The real part of .I y is chosen nonnegative. .LP One has: .nf cacosh(z) = 2 * clog(csqrt((z + 1) / 2) + csqrt((z \- 1) / 2)) .fi .SH VERSIONS These functions first appeared in glibc in version 2.1. .SH CONFORMING TO C99. .SH EXAMPLE .nf /* Link with "\-lm" */ #include #include #include #include int main(int argc, char *argv[]) { double complex z, c, f; if (argc != 3) { fprintf(stderr, "Usage: %s \\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); } .fi .SH SEE ALSO .BR acosh (3), .BR cabs (3), .BR ccosh (3), .BR cimag (3), .BR complex (7)