catanf


SYNOPSIS
       #include <complex.h>

       double complex catan(double complex z);
       float complex catanf(float complex z);
       long double complex catanl(long double complex z);

       Link with -lm.

DESCRIPTION
       The  catan()  function  calculates  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)

VERSIONS
       These functions first appeared in glibc in version 2.1.

CONFORMING TO
       C99.

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 = 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(f2), cimag(f2));

           exit(EXIT_SUCCESS);
       }
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