/// <summary>
/// Householder Reflection: Evaluate symmetric? unitary Q such that Q*v = -sigma*||v||*e1
/// </summary>
public static ComplexMatrix Reflection(ComplexVector v)
{
Complex sigma = v[0].Sign;
ComplexVector u = v.Clone();
u[0] += sigma * v.Norm();
ComplexMatrix m = ComplexMatrix.Identity(v.Length, v.Length);
m.MultiplyAccumulateInplace(u.TensorMultiply(u), -2d / u.ScalarMultiply(u));
return(m);
}
