17-numcxx-cg.cxx File Reference

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Functions
int	main (void)

Function Documentation

int main

(

void

)

Definition at line 14 of file 17-numcxx-cg.cxx.

{
  int n=5000; // problem size
  int max_iter=100; // maximum number of iterations
  double tol=1.0e-14; // tolerance
  
  auto pA=numcxx::DSparseMatrix::create(n,n);
  auto pF=numcxx::DArray1::create(n);
  auto pU=numcxx::DArray1::create(n);
  
  auto &A=*pA;
  auto &F=*pF;
  auto &U=*pU;
  
  F=1.0;
  for (int i=0;i<n;i++)
  {
    A(i,i)=3.0;
    if (i>0) A(i,i-1)=-1;
    if (i<n-1) A(i,i+1)=-1;
  }
  pA->flush();
  
  
  auto pJacobi=numcxx::DPreconJacobi::create(pA);
  numcxx::TPreconJacobi<double> JacobiSolver(pA);

  
  U=0.0;
  netlib::CG(A,U,F,*pJacobi,max_iter,tol);
  double residual=normi(A*U-F);
  std::cout << "residual:" << residual << std::endl;
}

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