Other Alias
cacos, cacoslSYNOPSIS
#include <complex.h>
double complex cacos(double complex z);
float complex cacosf(float complex z);
long double complex cacosl(long double complex z);
Link with -lm.
DESCRIPTION
These functions calculate the complex arc cosine of z. If y = cacos(z), then z = ccos(y). The real part of y is chosen in the interval [0,pi].One has:
cacos(z) = -i * clog(z + i * csqrt(1 - z * z))
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 |
cacos(), cacosf(), cacosl() | 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; double complex i = I; if (argc != 3) { fprintf(stderr, "Usage: %s <real> <imag>\n", argv[0]); exit(EXIT_FAILURE); } z = atof(argv[1]) + atof(argv[2]) * I; c = cacos(z); printf("cacos() = %6.3f %6.3f*i\n", creal(c), cimag(c)); f = -i * clog(z + i * csqrt(1 - z * z)); printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f)); exit(EXIT_SUCCESS); }
COLOPHON
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