#include <complex.h> 
#include <tgmath.h>
#include <assert.h>

int
main(int argc, char **argv)
{
        double _Complex testcase = -INFINITY * NAN*I;

        double _Complex r = atan(testcase);
        double _Complex t1 = (-cimag(testcase), creal(testcase));
        double _Complex t2 = atanh(t1);
        double _Complex z = cimag(t2) * - creal(t2) * I;

        if (isnan(creal(r))) {
                assert(isnan(creal(z)));
        } else {
                assert(creal(r) == creal(z));
                assert(signbit(creal(r)) == signbit(creal(z)));
        }

        if (isnan(cimag(r))) {
                assert(isnan(cimag(z)));
        } else {
                assert(cimag(r) == cimag(z));
                assert(signbit(cimag(r)) == signbit(cimag(z)));
        }

        return 0;

}