Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/libigl/igl/null.cpp

@@ -0,0 +1,21 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2015 Alec Jacobson <alecjacobson@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+#include "null.h"
+#include "EPS.h"
+
+template <typename DerivedA, typename DerivedN>
+IGL_INLINE void igl::null(
+  const Eigen::PlainObjectBase<DerivedA> & A,
+  Eigen::PlainObjectBase<DerivedN> & N)
+{
+  using namespace Eigen;
+  typedef typename DerivedA::Scalar Scalar;
+  JacobiSVD<MatrixXd> svd(A, ComputeFullV);
+  svd.setThreshold(A.cols() * svd.singularValues().maxCoeff() * EPS<Scalar>());
+  N = svd.matrixV().rightCols(A.cols()-svd.rank());
+}