Function SNF

FHE/Matrix.cpp:212–237

S = U*A*V

// S = U*A*V
void SNF(matrix& S,const matrix& A,matrix& V)
{
  int m=A.size(),n=A[0].size();

#ifdef VERBOSE
  cerr << "SNF m=" << m << ", n=" << n << endl;
#endif

  S=A;
  ident(V,n);

  /* First get a diagonal matrix using the HNF */
  matrix U2,V2;
  SNF_Step(S,V); 

  /* Now get the divisibility condition */
  int i,r;
  r=min(m,n);
  for (i=0; i<r-1; i++)
    { if ((S[i+1][i+1]%S[i][i])!=0)
	{ // Add row i+1 to row i
	  S[i][i+1]=S[i+1][i+1];
          SNF_Step(S,V);
	}
    }
}