Eigen::MetisOrdering< StorageIndex > Class Template Reference

#include <MetisSupport.h>

Collaboration diagram for Eigen::MetisOrdering< StorageIndex >:

List of all members.

Public Types
typedef PermutationMatrix < Dynamic, Dynamic, StorageIndex >	PermutationType
typedef Matrix< StorageIndex, Dynamic, 1 >	IndexVector
Public Member Functions
template<typename MatrixType >
void	get_symmetrized_graph (const MatrixType &A)
template<typename MatrixType >
void	operator() (const MatrixType &A, PermutationType &matperm)
Protected Attributes
IndexVector	m_indexPtr
IndexVector	m_innerIndices

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Detailed Description

template<typename StorageIndex>
class Eigen::MetisOrdering< StorageIndex >

Get the fill-reducing ordering from the METIS package

If A is the original matrix and Ap is the permuted matrix, the fill-reducing permutation is defined as follows : Row (column) i of A is the matperm(i) row (column) of Ap. WARNING: As computed by METIS, this corresponds to the vector iperm (instead of perm)

Definition at line 22 of file MetisSupport.h.

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Member Typedef Documentation

template<typename StorageIndex >

typedef Matrix<StorageIndex,Dynamic,1> Eigen::MetisOrdering< StorageIndex >::IndexVector

Definition at line 26 of file MetisSupport.h.

template<typename StorageIndex >

typedef PermutationMatrix<Dynamic,Dynamic,StorageIndex> Eigen::MetisOrdering< StorageIndex >::PermutationType

Definition at line 25 of file MetisSupport.h.

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Member Function Documentation

template<typename StorageIndex >

template<typename MatrixType >

void Eigen::MetisOrdering< StorageIndex >::get_symmetrized_graph

(

const MatrixType &

A

)

[inline]

Definition at line 29 of file MetisSupport.h.

  {
    Index m = A.cols(); 
    eigen_assert((A.rows() == A.cols()) && "ONLY FOR SQUARED MATRICES");
    // Get the transpose of the input matrix 
    MatrixType At = A.transpose(); 
    // Get the number of nonzeros elements in each row/col of At+A
    Index TotNz = 0; 
    IndexVector visited(m); 
    visited.setConstant(-1); 
    for (StorageIndex j = 0; j < m; j++)
    {
      // Compute the union structure of of A(j,:) and At(j,:)
      visited(j) = j; // Do not include the diagonal element
      // Get the nonzeros in row/column j of A
      for (typename MatrixType::InnerIterator it(A, j); it; ++it)
      {
        Index idx = it.index(); // Get the row index (for column major) or column index (for row major)
        if (visited(idx) != j ) 
        {
          visited(idx) = j; 
          ++TotNz; 
        }
      }
      //Get the nonzeros in row/column j of At
      for (typename MatrixType::InnerIterator it(At, j); it; ++it)
      {
        Index idx = it.index(); 
        if(visited(idx) != j)
        {
          visited(idx) = j; 
          ++TotNz; 
        }
      }
    }
    // Reserve place for A + At
    m_indexPtr.resize(m+1);
    m_innerIndices.resize(TotNz); 

    // Now compute the real adjacency list of each column/row 
    visited.setConstant(-1); 
    StorageIndex CurNz = 0; 
    for (StorageIndex j = 0; j < m; j++)
    {
      m_indexPtr(j) = CurNz; 
      
      visited(j) = j; // Do not include the diagonal element
      // Add the pattern of row/column j of A to A+At
      for (typename MatrixType::InnerIterator it(A,j); it; ++it)
      {
        StorageIndex idx = it.index(); // Get the row index (for column major) or column index (for row major)
        if (visited(idx) != j ) 
        {
          visited(idx) = j; 
          m_innerIndices(CurNz) = idx; 
          CurNz++; 
        }
      }
      //Add the pattern of row/column j of At to A+At
      for (typename MatrixType::InnerIterator it(At, j); it; ++it)
      {
        StorageIndex idx = it.index(); 
        if(visited(idx) != j)
        {
          visited(idx) = j; 
          m_innerIndices(CurNz) = idx; 
          ++CurNz; 
        }
      }
    }
    m_indexPtr(m) = CurNz;    
  }

template<typename StorageIndex >

template<typename MatrixType >

void Eigen::MetisOrdering< StorageIndex >::operator()	(	const MatrixType &	A,
		PermutationType &	matperm
	)		[inline]

Definition at line 103 of file MetisSupport.h.

  {
     StorageIndex m = internal::convert_index<StorageIndex>(A.cols()); // must be StorageIndex, because it is passed by address to METIS
     IndexVector perm(m),iperm(m); 
    // First, symmetrize the matrix graph. 
     get_symmetrized_graph(A); 
     int output_error;
     
     // Call the fill-reducing routine from METIS 
     output_error = METIS_NodeND(&m, m_indexPtr.data(), m_innerIndices.data(), NULL, NULL, perm.data(), iperm.data());
     
    if(output_error != METIS_OK) 
    {
      //FIXME The ordering interface should define a class of possible errors 
     std::cerr << "ERROR WHILE CALLING THE METIS PACKAGE \n"; 
     return; 
    }
    
    // Get the fill-reducing permutation 
    //NOTE:  If Ap is the permuted matrix then perm and iperm vectors are defined as follows 
    // Row (column) i of Ap is the perm(i) row(column) of A, and row (column) i of A is the iperm(i) row(column) of Ap
    
     matperm.resize(m);
     for (int j = 0; j < m; j++)
       matperm.indices()(iperm(j)) = j;
   
  }

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Member Data Documentation

template<typename StorageIndex >

IndexVector Eigen::MetisOrdering< StorageIndex >::m_indexPtr [protected]

Definition at line 132 of file MetisSupport.h.

template<typename StorageIndex >

IndexVector Eigen::MetisOrdering< StorageIndex >::m_innerIndices [protected]

Definition at line 133 of file MetisSupport.h.

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The documentation for this class was generated from the following file:

• MetisSupport.h