ccot

Complex circular cotangent.

SYNOPSIS:

void ccot();
cmplx z, w;

ccot(&z, &w);

DESCRIPTION:

If
     z = x + iy,

then

           sin 2x - i sinh 2y
     w = --------------------.
            cosh 2y - cos 2x

On the real axis, the denominator has zeros at even multiples of PI/2. Near these points it is evaluated by a Taylor series.

ACCURACY:

                      Relative error:
arithmetic   domain     # trials      peak         rms
    DEC       -10,+10      3000       6.5e-17     1.6e-17
    IEEE      -10,+10     30000       9.2e-16     1.2e-16

Also tested by ctan * ccot = 1 + i0.