/home/vivien/public_html/.src_seldon/computation/solver/SparseCholeskyFactorisation.cxx

// Copyright (C) 2010 Marc Duruflé
//
// This file is part of the linear-algebra library Seldon,
// http://seldon.sourceforge.net/.
//
// Seldon is free software; you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License as published by the Free
// Software Foundation; either version 2.1 of the License, or (at your option)
// any later version.
//
// Seldon is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
// more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Seldon. If not, see http://www.gnu.org/licenses/.


#ifndef SELDON_FILE_SPARSE_CHOLESKY_FACTORISATION_CXX

#include "Ordering.cxx"
#include "SparseCholeskyFactorisation.hxx"

namespace Seldon
{


  template<class T, class Prop, class Allocator>
  void GetCholesky(Matrix<T, Prop, ArrayRowSymSparse, Allocator>& A,
                   int print_level = 0)
  {
    int n = A.GetN();
    T t, s, fact;
    int j_col, jrow, index_lu, jpos;
    Vector<T> Row_Val(n);
    IVect Index(n), Row_Ind(n);
    Row_Val.Fill(0);
    Row_Ind.Fill(-1);

    Index.Fill(-1);

    // Conversion to unsymmetric matrix.
    Matrix<T, General, ArrayRowSparse, Allocator> B;
    Copy(A, B);

    // A is cleared.
    A.Clear();
    A.Reallocate(n, n);

    // Main loop over rows.
    int new_percent = 0, old_percent = 0;
    for (int i_row = 0; i_row < n; i_row++)
      {
        // Progress bar if print level is high enough.
        if (print_level > 0)
          {
            new_percent = int(double(i_row) / double(n-1) * 78.);
            for (int percent = old_percent; percent < new_percent; percent++)
              {
                cout << "#";
                cout.flush();
              }
            old_percent = new_percent;
          }

        int size_row = B.GetRowSize(i_row);

        // we are separating lower from upper part
        int length_lower = 0, length_upper = 1;
        Row_Ind(i_row) = i_row;
        Row_Val(i_row) = 0.0;
        Index(i_row) = i_row;

        for (int j = 0; j < size_row; j++)
          {
            int k = B.Index(i_row, j);
            t = B.Value(i_row, j);
            if (k < i_row)
              {
                Row_Ind(length_lower) = k;
                Row_Val(length_lower) = t;
                Index(k) = length_lower;
                length_lower++;
              }
            else if (k == i_row)
              Row_Val(i_row) = t;
            else
              {
                jpos = i_row + length_upper;
                Row_Ind(jpos) = k;
                Row_Val(jpos) = t;
                Index(k) = jpos;
                length_upper++;
              }
          }

        B.ClearRow(i_row);

        j_col = 0;
        int length = 0;

        // Previous rows are eliminated.
        while (j_col < length_lower)
          {
            jrow = Row_Ind(j_col);

            // We search first element in lower part.
            int k = j_col;
            for (int j = (j_col+1) ; j < length_lower; j++)
              {
                if (Row_Ind(j) < jrow)
                  {
                    jrow = Row_Ind(j);
                    k = j;
                  }
              }


            if (k != j_col)
              {
                // If k different from j_col, we are exchanging positions.
                int j = Row_Ind(j_col);
                Row_Ind(j_col) = Row_Ind(k);
                Row_Ind(k) = j;

                Index(jrow) = j_col;
                Index(j) = k;

                s = Row_Val(j_col);
                Row_Val(j_col) = Row_Val(k);
                Row_Val(k) = s;
              }

            // Zero out element in row.
            Index(jrow) = -1;
            fact = Row_Val(j_col) * A.Value(jrow, 0);

            // Combines current row and row jrow.
            for (int k = 1; k < A.GetRowSize(jrow); k++)
              {
                s = fact * A.Value(jrow, k);
                int j = A.Index(jrow, k);

                jpos = Index(j);
                if (j >= i_row)
                  {
                    // Dealing with upper part.
                    if (jpos == -1)
                      {
                        // This is a fill-in element.
                        int i = i_row + length_upper;
                        Row_Ind(i) = j;
                        Index(j) = i;
                        Row_Val(i) = -s;
                        length_upper++;
                      }
                    else
                      {
                        // This is not a fill-in element.
                        Row_Val(jpos) -= s;
                      }
                  }
                else
                  {
                    // Dealing  with lower part.
                    if (jpos == -1)
                      {
                        // This is a fill-in element.
                        Row_Ind(length_lower) = j;
                        Index(j) = length_lower;
                        Row_Val(length_lower) = -s;
                        length_lower++;
                      }
                    else
                      {
                        // This is not a fill-in element.
                        Row_Val(jpos) -= s;
                      }
                  }
              }

            // Stores this pivot element
            // (from left to right -- no danger of overlap
            // with the working elements in L (pivots).
            Row_Val(length) = fact;
            Row_Ind(length) = jrow;
            ++length;
            j_col++;
          }

        for (int k = 0; k < length_upper; k++)
          Index(Row_Ind(i_row + k)) = -1;

        // Now we can store the uppert part of row.
        size_row = length_upper;
        A.ReallocateRow(i_row, length_upper);

        // We store inverse of square root of diagonal element of u.
        if (Row_Val(i_row) <= 0)
          {
            cout << "Error during Cholesky factorization " << endl;
            cout << "Matrix must be definite positive " << endl;
            cout << "but diagonal element of row " << i_row
                 << "is equal to " << Row_Val(i_row) << endl;

#ifdef SELDON_WITH_ABORT
            abort();
#endif
          }

        A.Value(i_row, 0) = 1.0 / Row_Val(i_row);
        A.Index(i_row, 0) = i_row;
        index_lu = 1;

        // and extra-diagonal terms
        for (int k = i_row + 1; k < i_row + length_upper; k++)
          {
            A.Index(i_row, index_lu) = Row_Ind(k);
            A.Value(i_row, index_lu) = Row_Val(k);
            index_lu++;
          }
      }

    if (print_level > 0)
      {
        cout << endl;
        cout << "The matrix takes " <<
          int((A.GetDataSize() * (sizeof(T)+4)) / (1024*1024)) << " MB" << endl;
      }

    // Diagonal of A is replaced by its square root.
    for (int i = 0; i < n; i++)
      {
        A.Value(i, 0) = sqrt(A.Value(i,0));
        // and other elements multiplied by this value.
        for (int k = 1; k < A.GetRowSize(i); k++)
          A.Value(i, k) *= A.Value(i, 0);

        A.Value(i, 0) = 1.0 / A.Value(i, 0);
      }
  }



  template<class classTrans,
           class T0, class T1, class Prop, class Storage,
           class Allocator1, class Allocator2>
  void SolveCholesky(const classTrans& TransA,
                     const Matrix<T0, Prop, ArrayRowSymSparse, Allocator1>& A,
                     Vector<T1, Storage, Allocator2>& x)
  {
    int n = A.GetM();
    if (n <= 0)
      return;

    if (TransA.Trans())
      {
        // We solve L^T x = x
        int j;
        for (int i = n - 1; i >= 0; i--)
          {
            T1 val = x(i);
            for (int k = 1; k < A.GetRowSize(i) ; k++)
              {
                j = A.Index(i, k);
                val -= A.Value(i, k) * x(j);
              }

            x(i) = val / A.Value(i, 0);
          }
      }
    else
      {
        // We solve L x = x
        int j;
        for (int i = 0; i < n; i++)
          {
            x(i) /= A.Value(i, 0);
            for (int k = 1; k < A.GetRowSize(i) ; k++)
              {
                j = A.Index(i, k);
                x(j) -= A.Value(i, k) * x(i);
              }
          }
      }
  }



  template<class classTrans,
           class T, class Prop, class Allocator>
  void SolveCholesky(const classTrans& TransA,
                     const Matrix<T, Prop, RowSymSparse>& A,
                     Vector<T, VectFull, Allocator>& X)
  {
    int n = A.GetM();
    if (n <= 0)
      return;

    int* ind = A.GetInd();
    int* ptr = A.GetPtr();
    T* data = A.GetData();
    T val = 0;

    if (TransA.Trans())
      // Resolution of L^T x = x.
      for (int i = n - 1; i >= 0; i--)
        {
          val = X(i);
          for (int j = ptr[i] + 1; j < ptr[i+1]; j++)
            val -= data[j] * X(ind[j]);

          X(i) = val / data[ptr[i]];
        }
    else
      // Resolution of L x = x.
      for (int i = 0; i < n; i++)
        {
          X(i) /= data[ptr[i]];
          for (int j = ptr[i] + 1; j < ptr[i+1]; j++)
            X(ind[j]) -= data[j] * X(i);
        }
  }



  template<class classTrans,
           class T0, class T1, class Prop, class Storage,
           class Allocator1, class Allocator2>
  void MltCholesky(const classTrans& TransA,
                   const Matrix<T0, Prop, ArrayRowSymSparse, Allocator1>& A,
                   Vector<T1, Storage, Allocator2>& x)
  {
    int n = A.GetM();
    if (n <= 0)
      return;

    if (TransA.Trans())
      {
        // We overwrite x by L^T x
        int j;
        for (int i = 0; i < n; i++)
          {
            T1 val = x(i) * A.Value(i, 0);
            for (int k = 1; k < A.GetRowSize(i) ; k++)
              {
                j = A.Index(i, k);
                val += A.Value(i, k)*x(j);
              }

            x(i) = val;
          }
      }
    else
      {
        // We overwrite x with L x
        int j;
        for (int i = n - 1; i >= 0; i--)
          {
            for (int k = 1; k < A.GetRowSize(i) ; k++)
              {
                j = A.Index(i, k);
                x(j) += A.Value(i, k)*x(i);
              }

            x(i) *= A.Value(i, 0);
          }
      }
  }



  template<class classTrans,
           class T0, class T1, class Prop, class Storage,
           class Allocator1, class Allocator2>
  void MltCholesky(const classTrans& TransA,
                   const Matrix<T0, Prop, RowSymSparse, Allocator1>& A,
                   Vector<T1, Storage, Allocator2>& x)
  {
    int n = A.GetM();
    if (n <= 0)
      return;

    int* ind = A.GetInd();
    int* ptr = A.GetPtr();
    T1* data = A.GetData();
    T1 val = 0;

    if (TransA.Trans())
      // We overwrite x by L^T x.
      for (int i = 0; i < n; i++)
        {
          val = x(i) * data[ptr[i]];
          for (int k = ptr[i] + 1; k < ptr[i+1]; k++)
            val += data[k] * x(ind[k]);

          x(i) = val;
        }
    else
      // We overwrite x by L x.
      for (int i = n - 1; i >= 0; i--)
        {
          for (int k = ptr[i] + 1; k < ptr[i+1]; k++)
            x(ind[k]) += data[k] * x(i);

          x(i) *= data[ptr[i]];
        }
  }


  // SPARSECHOLESKYSOLVER //


  template<class T>
  SparseCholeskySolver<T>::SparseCholeskySolver()
  {
    n = 0;
    print_level = -1;
    type_ordering = SparseMatrixOrdering::IDENTITY;

    type_solver = SELDON_SOLVER;
#ifdef SELDON_WITH_CHOLMOD
    type_solver = CHOLMOD;
#endif
  }


  template<class T>
  void SparseCholeskySolver<T>::HideMessages()
  {
    print_level = -1;

#ifdef SELDON_WITH_CHOLMOD
    mat_chol.HideMessages();
#endif

  }


  template<class T>
  void SparseCholeskySolver<T>::ShowMessages()
  {
    print_level = 1;

#ifdef SELDON_WITH_CHOLMOD
    mat_chol.ShowMessages();
#endif

  }


  template<class T>
  void SparseCholeskySolver<T>::ShowFullHistory()
  {
    print_level = 3;

#ifdef SELDON_WITH_CHOLMOD
    mat_chol.ShowMessages();
#endif

  }


  template<class T>
  void SparseCholeskySolver<T>::Clear()
  {
    if (n > 0)
      {
        n = 0;

#ifdef SELDON_WITH_CHOLMOD
        mat_chol.Clear();
#endif

        mat_sym.Clear();
      }
  }


  template<class T>
  int SparseCholeskySolver<T>::GetM() const
  {
    return n;
  }


  template<class T>
  int SparseCholeskySolver<T>::GetN() const
  {
    return n;
  }


  template<class T>
  int SparseCholeskySolver<T>::GetTypeOrdering() const
  {
    return type_ordering;
  }


  template<class T>
  void SparseCholeskySolver<T>::SetOrdering(const IVect& num)
  {
    type_ordering = SparseMatrixOrdering::USER;
    permutation = num;
  }


  template<class T>
  void SparseCholeskySolver<T>::SelectOrdering(int type)
  {
    type_ordering = type;
  }


  template<class T>
  void SparseCholeskySolver<T>::SelectDirectSolver(int type)
  {
    type_solver = type;
  }


  template<class T>
  int SparseCholeskySolver<T>::GetDirectSolver()
  {
    return type_solver;
  }


  template<class T> template<class MatrixSparse>
  void SparseCholeskySolver<T>::Factorize(MatrixSparse& A, bool keep_matrix)
  {
    n = A.GetM();
    if (type_solver == CHOLMOD)
      {
#ifdef SELDON_WITH_CHOLMOD
        mat_chol.FactorizeMatrix(A, keep_matrix);
#else
        throw Error("SparseCholeskySolver::Factorize",
                    "Recompile with Cholmod or change solver type.");
#endif
      }
    else
      {
        FindSparseOrdering(A, permutation, type_ordering);
        Copy(A, mat_sym);
        if (!keep_matrix)
          A.Clear();

        ApplyInversePermutation(mat_sym, permutation, permutation);

        GetCholesky(mat_sym, print_level);
        xtmp.Reallocate(n);
      }
  }


  template<class T> template<class TransStatus, class Vector1>
  void SparseCholeskySolver<T>
  ::Solve(const TransStatus& TransA, Vector1& x_solution)
  {
    if (type_solver == CHOLMOD)
      {
#ifdef SELDON_WITH_CHOLMOD
        mat_chol.Solve(TransA, x_solution);
#else
        throw Error("SparseCholeskySolver::Factorize",
                    "Recompile with Cholmod or change solver type.");
#endif
      }
    else
      if (TransA.NoTrans())
        {
          for (int i = 0; i < x_solution.GetM(); i++)
            xtmp(permutation(i)) = x_solution(i);

          SolveCholesky(TransA, mat_sym, xtmp);
          Copy(xtmp, x_solution);
        }
      else
        {
          Copy(x_solution, xtmp);
          SolveCholesky(TransA, mat_sym, xtmp);

          for (int i = 0; i < x_solution.GetM(); i++)
            x_solution(i) = xtmp(permutation(i));
        }
  }


  template<class T> template<class TransStatus, class Vector1>
  void SparseCholeskySolver<T>
  ::Mlt(const TransStatus& TransA, Vector1& x_solution)
  {
    if (type_solver == CHOLMOD)
      {
#ifdef SELDON_WITH_CHOLMOD
        mat_chol.Mlt(TransA, x_solution);
#else
        throw Error("SparseCholeskySolver::Factorize",
                    "Recompile with Cholmod or change solver type.");
#endif
      }
    else
      if (TransA.NoTrans())
        {
          Copy(x_solution, xtmp);
          MltCholesky(TransA, mat_sym, xtmp);

          for (int i = 0; i < x_solution.GetM(); i++)
            x_solution(i) = xtmp(permutation(i));
        }
      else
        {
          for (int i = 0; i < x_solution.GetM(); i++)
            xtmp(permutation(i)) = x_solution(i);

          MltCholesky(TransA, mat_sym, xtmp);
          Copy(xtmp, x_solution);
        }
  }

} // namespace Seldon.


#define SELDON_FILE_SPARSE_CHOLESKY_FACTORISATION_CXX
#endif