HYPRE并行库进行稀疏线性方程组求解

将矩阵处理成IJ接口形式

HYPRE_IJMatrixCreate(MPI_COMM_WORLD, ilower, iupper, ilower, iupper, &A);

HYPRE_IJMatrixSetObjectType(A, HYPRE_PARCSR);

//设置值之前先初始化

HYPRE_IJMatrixInitialize(A);

for (i = ilower; i <= iupper; i++)

HYPRE_IJMatrixSetValues(A, 1, &nnz, &i, cols, values);

HYPRE_IJMatrixAssemble(A);

//对parcsr_A使用

HYPRE_IJMatrixGetObject(A, (void**) &parcsr_A);

无预处理求解

      //建立求解器
      HYPRE_ParCSRPCGCreate(MPI_COMM_WORLD, &solver);


      //设置参数
      HYPRE_PCGSetMaxIter(solver, 1000); /* max iterations */
      HYPRE_PCGSetTol(solver, 1e-7); /* conv. tolerance */
      HYPRE_PCGSetTwoNorm(solver, 1); /* use the two norm as the stopping criteria */
      HYPRE_PCGSetPrintLevel(solver, 2); /* prints out the iteration info */
      HYPRE_PCGSetLogging(solver, 1); /* needed to get run info later */


      /* Now setup and solve! */
      HYPRE_ParCSRPCGSetup(solver, parcsr_A, par_b, par_x);
      HYPRE_ParCSRPCGSolve(solver, parcsr_A, par_b, par_x);


      //一些统计数据 
      HYPRE_PCGGetNumIterations(solver, &num_iterations);
      HYPRE_PCGGetFinalRelativeResidualNorm(solver, &final_res_norm);

      /* Destroy solver */
      HYPRE_ParCSRPCGDestroy(solver);

有预处理求解

     /* Create solver */
      HYPRE_ParCSRPCGCreate(MPI_COMM_WORLD, &solver);


      /* Set some parameters (See Reference Manual for more parameters) */
      HYPRE_PCGSetMaxIter(solver, 1000); /* max iterations */
      HYPRE_PCGSetTol(solver, 1e-7); /* conv. tolerance */
      HYPRE_PCGSetTwoNorm(solver, 1); /* use the two norm as the stopping criteria */
      HYPRE_PCGSetPrintLevel(solver, 2); /* print solve info */
      HYPRE_PCGSetLogging(solver, 1); /* needed to get run info later */


      /* Now set up the ParaSails preconditioner and specify any parameters */
      HYPRE_ParaSailsCreate(MPI_COMM_WORLD, &precond);


      /* Set some parameters (See Reference Manual for more parameters) */
      HYPRE_ParaSailsSetParams(precond, sai_threshold, sai_max_levels);
      HYPRE_ParaSailsSetFilter(precond, sai_filter);
      HYPRE_ParaSailsSetSym(precond, sai_sym);
      HYPRE_ParaSailsSetLogging(precond, 3);


      /* Set the PCG preconditioner */
      HYPRE_PCGSetPrecond(solver, (HYPRE_PtrToSolverFcn) HYPRE_ParaSailsSolve,
                          (HYPRE_PtrToSolverFcn) HYPRE_ParaSailsSetup, precond);


      /* Now setup and solve! */
      HYPRE_ParCSRPCGSetup(solver, parcsr_A, par_b, par_x);
      HYPRE_ParCSRPCGSolve(solver, parcsr_A, par_b, par_x);


      /* Run info - needed logging turned on */
      HYPRE_PCGGetNumIterations(solver, &num_iterations);
      HYPRE_PCGGetFinalRelativeResidualNorm(solver, &final_res_norm);


      /* Destory solver and preconditioner */
      HYPRE_ParCSRPCGDestroy(solver);
      HYPRE_ParaSailsDestroy(precond);