catan(3) Library Functions Manual catan(3) NAME catan, catanf, catanl - complex arc tangents LIBRARY Math library (libm, -lm) SYNOPSIS #include double complex catan(double complex z); float complex catanf(float complex z); long double complex catanl(long double complex z); DESCRIPTION These functions calculate the complex arc tangent of z. If y = catan(z), then z = ctan(y). The real part of y is chosen in the interval [-pi/2, pi/2]. One has: catan(z) = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i) ATTRIBUTES For an explanation of the terms used in this section, see attributes(7). +--------------------------------------------+---------------+---------+ |Interface | Attribute | Value | +--------------------------------------------+---------------+---------+ |catan (), catanf (), catanl () | 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 = catan(z); printf("catan() = %6.3f %6.3f*i\n", creal(c), cimag(c)); f = (clog(1 + i * z) - clog(1 - i * z)) / (2 * i); printf("formula = %6.3f %6.3f*i\n", creal(f), cimag(f)); exit(EXIT_SUCCESS); } SEE ALSO ccos(3), clog(3), ctan(3), complex(7) Linux man-pages 6.9.1 2024-06-15 catan(3)