cacos(3) Library Functions Manual cacos(3) NAME cacos, cacosf, cacosl - complex arc cosine LIBRARY Math library (libm, -lm) SYNOPSIS #include double complex cacos(double complex z); float complex cacosf(float complex z); long double complex cacosl(long double complex z); 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)) ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). +--------------------------------------------+---------------+---------+ |Interface | Attribute | Value | +--------------------------------------------+---------------+---------+ |cacos (), cacosf (), cacosl () | Thread safety | MT-Safe | +--------------------------------------------+---------------+---------+ STANDARDS C11, POSIX.1-2008. HISTORY glibc 2.1. C99, POSIX.1-2001. EXAMPLES /* Link with "-lm" */ #include #include #include #include int main(int argc, char *argv[]) { double complex z, c, f; double complex i = I; if (argc != 3) { fprintf(stderr, "Usage: %s \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); } SEE ALSO ccos(3), clog(3), complex(7) Linux man-pages 6.9.1 2024-06-15 cacos(3)