RComplex(const RScalar<T1>& _re, const RScalar<T2>& _im): re(_re.elem()), im(_im.elem()) {}
RComplex(const T1& _re, const T2& _im): re(_re), im(_im) {}
  RComplex(const RScalar<T1>& _re, const RScalar<T2>& _im): re(_re.elem()), im(_im.elem()) {}