eigs in tutorial

Former-commit-id: 1a5d6b8328f056dfec6f53e10bb2bf409c48f75b

tutorial/306_EigenDecomposition/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 2.6)
+project(306_EigenDecomposition)
+
+include("../CMakeLists.shared")
+
+set(SOURCES
+${PROJECT_SOURCE_DIR}/main.cpp
+)
+
+add_executable(${PROJECT_NAME}_bin ${SOURCES} ${SHARED_SOURCES})
+target_link_libraries(${PROJECT_NAME}_bin ${SHARED_LIBRARIES})

tutorial/306_EigenDecomposition/main.cpp

@@ -0,0 +1,68 @@
+#include <igl/eigs.h>
+#include <igl/cotmatrix.h>
+#include <igl/massmatrix.h>
+#include <igl/Viewer/viewer.h>
+#include <igl/parula.h>
+#include <Eigen/Sparse>
+#include <iostream>
+#include <queue>
+
+Eigen::MatrixXd V,U;
+Eigen::MatrixXi F;
+int c=0;
+double bbd = 1;
+bool twod = 0;
+int main(int argc, char * argv[])
+{
+  using namespace Eigen;
+  using namespace std;
+  using namespace igl;
+  VectorXd D;
+  if(!read_triangle_mesh("../shared/beetle.off",V,F))
+  {
+    cout<<"failed to load mesh"<<endl;
+  }
+  twod = V.col(2).minCoeff()==V.col(2).maxCoeff();
+  bbd = (V.colwise().maxCoeff()-V.colwise().minCoeff()).norm();
+  SparseMatrix<double> L,M;
+  cotmatrix(V,F,L);
+  L = (-L).eval();
+  massmatrix(V,F,MASSMATRIX_TYPE_DEFAULT,M);
+  const size_t k = 5;
+  if(!eigs(L,M,k+1,EIGS_TYPE_SM,U,D))
+  {
+    cout<<"failed."<<endl;
+  }
+  U = ((U.array()-U.minCoeff())/(U.maxCoeff()-U.minCoeff())).eval();
+
+  igl::viewer::Viewer viewer;
+  viewer.callback_key_down = [&](igl::viewer::Viewer & viewer,unsigned char key,int)->bool
+  {
+    switch(key)
+    {
+      default: 
+        return false;
+      case ' ':
+      {
+        U = U.rightCols(k).eval();
+        // Rescale eigen vectors for visualization
+        VectorXd Z = 
+          bbd*0.5*U.col(c);
+        Eigen::MatrixXd C;
+        igl::parula(U.col(c).eval(),false,C);
+        c = (c+1)%U.cols();
+        if(twod)
+        {
+          V.col(2) = Z;
+        }
+        viewer.data.set_mesh(V,F);
+        viewer.data.compute_normals();
+        viewer.data.set_colors(C);
+        return true;
+      }
+    }
+  };
+  viewer.callback_key_down(viewer,' ',0);
+  viewer.core.show_lines = false;
+  viewer.launch();
+}

tutorial/CMakeLists.txt

@@ -77,6 +77,7 @@ add_subdirectory("302_Sort")
 add_subdirectory("303_LaplaceEquation")
 add_subdirectory("304_LinearEqualityConstraints")
 add_subdirectory("305_QuadraticProgramming")
+add_subdirectory("306_EigenDecomposition")
 
 # Chapter 4
 add_subdirectory("401_BiharmonicDeformation")

tutorial/shared/beetle.off.REMOVED.git-id

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+565ca529a5b159e79a9afed0973091c55b942f9f

tutorial/tutorial.html.REMOVED.git-id

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+d33e7bea8bd2af6f2a712fee53098e93ae9e5f5d

tutorial/tutorial.md.REMOVED.git-id

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-d01b1d08eed6f827504ca91822bfa23543c7858d
+ad07b355eec052eaa2e00fd6d5daaf5120689ad7