r->r = expx * cos(z->i); r->i = expx * sin(z->i);
res.r = expx * cos(z->i); res.i = expx * sin(z->i);  resx->r = res.r; resx->i = res.i;
void c_exp(complex *r, complex *z)#endif{double expx;expx = exp(z->r);r->r = expx * cos(z->i);r->i = expx * sin(z->i);}