/// <summary>Trigonometric Cotangent (cot, Cotangens) of this <c>Complex</c>.</summary>
public Complex Cotangent()
{
if (IsReal)
{
return(new Complex(Trig.Cotangent(real), 0d));
}
double sinr = Trig.Sine(real);
double sinhi = Trig.HyperbolicSine(imag);
double denom = sinr * sinr + sinhi * sinhi;
return(new Complex(sinr * Trig.Cosine(real) / denom, -sinhi * Trig.HyperbolicCosine(imag) / denom));
}
