TridiagonalSolver.h

#ifndef PSCF_TRIDIAGONAL_SOLVER_H
#define PSCF_TRIDIAGONAL_SOLVER_H
 
/*
* PSCF - Polymer Self-Consistent Field Theory
*
* Copyright 2016 - 2022, The Regents of the University of Minnesota
* Distributed under the terms of the GNU General Public License.
*/
 
#include <util/containers/DArray.h>
 
#include <string>
#include <iostream>
 
 
namespace Pscf 
{
 
   using namespace Util;
 
   class TridiagonalSolver
   {
   public:
 
      TridiagonalSolver();
 
      ~TridiagonalSolver();
 
      void allocate(int n);
 
      void computeLU(const DArray<double>& d, const DArray<double>& u);
 
      void computeLU(const DArray<double>& d, 
                     const DArray<double>& u,
                     const DArray<double>& l);
 
      void multiply(const DArray<double>& b, DArray<double>& x);
 
      void solve(const DArray<double>& b, DArray<double>& x);
 
   private:
 
      // Diagonal elements
      DArray<double> d_;
 
      // Upper off-diagonal elements (unmodified by computeLU)
      DArray<double> u_;
 
      // Lower off-diagonal elements (replaced by multipliers)
      DArray<double> l_;
 
      // Work space.
      DArray<double> y_;
 
      int n_;
 
      // Apply Gauss elimination to private arrays d_, u_, l_.
      void gaussElimination();
 
   };
 
}
#endif