mul method
Implementation
MathComplex mul( dynamic r ){
if( r is MathComplex ){
if( r._im == 0.0 ){
return MathComplex( _re * r._re, _im * r._re );
}
return MathComplex( _re * r._re - _im * r._im, _re * r._im + _im * r._re );
}
double rr = ClipMath.toDouble(r);
return MathComplex( _re * rr, _im * rr );
}