Modify the butterfly C++ to handle a matrix size program argument + keep using...

Modify the butterfly C++ to handle a matrix size program argument + keep using JacobiSVD (instead of BDCSVD) on Windows VS.

misc/test/src/C++/hierarchicalFactorizationButterfly.cpp.in

@@ -12,7 +12,12 @@ using namespace std;
 
 int main(int argc, char** argv)
 {
-	auto wht = TransformHelper<FPP,Cpu>::hadamardFaust(10, false);
+	int log2dim;
+	if(argc > 2)
+		log2dim = std::atoi(argv[2]);
+	else
+		log2dim = 10;
+	auto wht = TransformHelper<FPP,Cpu>::hadamardFaust(log2dim, false);
 	Faust::MatDense<FPP,Cpu> A;
 	/********** NOTE: a lot of garbage is left here, it was useful during the first writing of butterfly module (it could be again) */
 	//	Faust::MatDense<FPP,Cpu> support1, support2, A;

src/faust_linear_operator/CPU/faust_MatDense.hpp

@@ -1260,7 +1260,13 @@ bool MatDense<FPP,Cpu>::eq_rows(const MatDense<FPP, Cpu> & other, faust_unsigned
 template<typename FPP>
 void MatDense<FPP, Cpu>::best_low_rank(const int &r, MatDense<FPP,Cpu> &bestX, MatDense<FPP, Cpu> &bestY) const
 {
+#ifdef _MSC_VER
+	// as far as I tested eigen3.4rc1 doesn't compile with VS 14
+	// so use JacobiSVD
+	Eigen::JacobiSVD<Eigen::Matrix<FPP, Eigen::Dynamic, Eigen::Dynamic>> svd(this->mat, Eigen::ComputeThinU | Eigen::ComputeThinV);
+#else
 	Eigen::BDCSVD<Eigen::Matrix<FPP, Eigen::Dynamic, Eigen::Dynamic>> svd(this->mat, Eigen::ComputeThinU | Eigen::ComputeThinV);
+#endif
 	if(bestX.getNbRow() != this->getNbRow() || r != bestX.getNbCol())
 		bestX.resize(this->getNbRow(), r);
 	if(bestY.getNbRow() != this->getNbRow() || r != bestY.getNbCol())