VNLSparseLUSolverTraits.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef VNLSparseLUSolverTraits_h
#define VNLSparseLUSolverTraits_h
 
// Deprecation bridge: VNLSparseLUSolverTraits (vnl_sparse_lu engine) is being
// replaced by SparseLUSolverTraits (Eigen::SparseLU), proven faster and
// more accurate. Eigen remains always available; only this VNL spelling is
// gated. The guard is silent by default, warns under ITK_LEGACY_REMOVE, and
// errors under ITK_FUTURE_LEGACY_REMOVE; ITK_LEGACY_TEST/SILENT opt out.
#if __has_include(<itkConfigure.h>)
#  include <itkConfigure.h>
#  if defined(ITK_FUTURE_LEGACY_REMOVE)
#    error "VNLSparseLUSolverTraits is removed; use SparseLUSolverTraits (SparseLUSolverTraits.h, Eigen::SparseLU)."
#  elif defined(ITK_LEGACY_REMOVE) && !defined(ITK_LEGACY_SILENT) && !defined(ITK_LEGACY_TEST)
#    if defined(_MSC_VER)
#      pragma message("VNLSparseLUSolverTraits is deprecated; migrate to SparseLUSolverTraits (Eigen::SparseLU).")
#    else
#      warning "VNLSparseLUSolverTraits is deprecated; migrate to SparseLUSolverTraits (Eigen::SparseLU)."
#    endif
#  endif
#endif
 
#include "vnl/vnl_vector.h"
#include "vnl/vnl_sparse_matrix.h"
#include "vnl/algo/vnl_sparse_lu.h"

template <typename T = double>
class VNLSparseLUSolverTraits
{
public:
  using ValueType = T;
  using MatrixType = vnl_sparse_matrix<ValueType>;
  using VectorType = vnl_vector<ValueType>;
  using SolverType = vnl_sparse_lu;

  static bool
  IsDirectSolver()
  {
    return true;
  }

  static MatrixType
  InitializeSparseMatrix(const unsigned int & iN)
  {
    return MatrixType(iN, iN);
  }

  static MatrixType
  InitializeSparseMatrix(const unsigned int & iRow, const unsigned int & iCol)
  {
    return MatrixType(iRow, iCol);
  }

  static VectorType
  InitializeVector(const unsigned int & iN)
  {
    return VectorType(iN);
  }

  static void
  FillMatrix(MatrixType & iA, const unsigned int & iR, const unsigned int & iC, const ValueType & iV)
  {
    iA(iR, iC) = iV;
  }

  static void
  AddToMatrix(MatrixType & iA, const unsigned int & iR, const unsigned int & iC, const ValueType & iV)
  {
    iA(iR, iC) += iV;
  }

  static void
  MatVecMult(const MatrixType & iA, const VectorType & iB, VectorType & oX)
  {
    iA.mult(iB, oX);
  }

  static bool
  Solve(const MatrixType & iA, const VectorType & iB, VectorType & oX)
  {
    SolverType solver(iA);
    Solve(solver, iB, oX);
 
    return true;
  }

  static bool
  Solve(const MatrixType & iA,
        const VectorType & iBx,
        const VectorType & iBy,
        const VectorType & iBz,
        VectorType &       oX,
        VectorType &       oY,
        VectorType &       oZ)
  {
    SolverType solver(iA);
    Solve(solver, iBx, iBy, iBz, oX, oY, oZ);
 
    return true;
  }

  static bool
  Solve(const MatrixType & iA, const VectorType & iBx, const VectorType & iBy, VectorType & oX, VectorType & oY)
  {
    SolverType solver(iA);
    Solve(solver, iBx, iBy, oX, oY);
 
    return true;
  }

  static void
  Solve(SolverType & solver, const VectorType & iB, VectorType & oX)
  {
    oX = solver.solve(iB);
  }

  static void
  Solve(SolverType &       solver,
        const VectorType & iBx,
        const VectorType & iBy,
        const VectorType & iBz,
        VectorType &       oX,
        VectorType &       oY,
        VectorType &       oZ)
  {
    oX = solver.solve(iBx);
    oY = solver.solve(iBy);
    oZ = solver.solve(iBz);
  }

  static void
  Solve(SolverType & solver, const VectorType & iBx, const VectorType & iBy, VectorType & oX, VectorType & oY)
  {
    oX = solver.solve(iBx);
    oY = solver.solve(iBy);
  }
};
 
#endif