/// <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)); }