libigl_Martin/examples/svd/example.cpp

#include <igl/svd.h>
#include <cstdlib>
#include <Accelerate/Accelerate.h>
#include <cstdio>

/* Auxiliary routines prototypes */
extern void print_matrix( char* desc, int m, int n, double* a, int lda );

/* Parameters */

void print3x3(const char * s, double * a)
{
  printf("%s =\n",s);
  for(int i = 0;i<3;i++)
  {
    for(int j = 0;j<3;j++)
    {
      printf("%g ",a[j*3+i]);
    }
    printf("\n");
  }
  printf("\n");
}

int main(int argc, char * argv[])
{
  //// List of rest positions
  ////        (0,1)
  ////         / \
  ////        /   \
  ////       /     \
  ////      /       \
  ////  (-1,0)-----(1,0)
  ////
  //double rest[3][3] = {
  //  {-1,0,0},
  //  {1,0,0},
  //  {0,1,0}};
  //// List of pose positions
  //// 
  //// (0,1)
  ////  |   \
  ////  |    \
  ////  |     (1,0)
  ////  |    /
  ////  |   /
  //// (0,-1)
  //double pose[3][3] = {
  //  {0,1,0},
  //  {0,-1,0},
  //  {1,0,0}};
  //// Compute covariance matrix C
  //double C[3*3];
  //// Initialize to zero
  //for(int i = 0;i<3*3;i++)
  //{
  //  C[i] = 0;
  //}

  //// Loop over vertices
  //for(int i = 0;i<3;i++)
  //{
  //  // Compute outer product rest[i] * pose[i]
  //  // Loop over coordinates
  //  for(int j = 0;j<3;j++)
  //  {
  //    // Loop over coordinates
  //    for(int k = 0;k<3;k++)
  //    {
  //      C[k*3+j] = rest[i][j] * pose[i][k];
  //    }
  //  }
  //}
  //print3x3("C",C);


  //
  //double C[3*3] = {8,3,4,1,5,9,6,7,2};
  double C[3*3] = {5242.55,3364,-0,-8170.15,-5242.56,0,-0,-0,0};
  double u[3*3],s[3],vt[3*3];
  print3x3("C",C);
  // Compute SVD of C
  igl::svd3x3(C,u,s,vt);
  print3x3("u",u);
  print3x3("vt",vt);

  // Compute R = u*vt
  double R[3*3];
  const double _3 = 3;
  const double _1 = 1;
  cblas_dgemm(CblasColMajor, CblasNoTrans,CblasNoTrans,3,3,3,1,u,3,vt,3,1,R,3);
  print3x3("RT (transposed to be row-major)",R);


  return 0;
}