/*BHEADER********************************************************************** * Copyright (c) 2008, Lawrence Livermore National Security, LLC. * Produced at the Lawrence Livermore National Laboratory. * This file is part of HYPRE. See file COPYRIGHT for details. * * HYPRE 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) version 2.1 dated February 1999. * * $Revision$ ***********************************************************************EHEADER*/ #include "_hypre_struct_ls.h" #include "smg.h" #define DEBUG 0 /*-------------------------------------------------------------------------- * This is the main solve routine for the Schaffer multigrid method. * This solver works for 1D, 2D, or 3D linear systems. The dimension * is determined by the hypre_StructStencilDim argument of the matrix * stencil. The hypre_StructGridDim argument of the matrix grid is * allowed to be larger than the dimension of the solver, and in fact, * this feature is used in the smaller-dimensional solves required * in the relaxation method for both the 2D and 3D algorithms. This * allows one to do multiple 2D or 1D solves in parallel (e.g., multiple * 2D solves, where the 2D problems are "stacked" planes in 3D). * The only additional requirement is that the linear system(s) data * be contiguous in memory. * * Notes: * - Iterations are counted as follows: 1 iteration consists of a * V-cycle plus an extra pre-relaxation. If the number of MG levels * is equal to 1, then only the extra pre-relaxation step is done at * each iteration. When the solver exits because the maximum number * of iterations is reached, the last extra pre-relaxation is not done. * This allows one to use the solver as a preconditioner for conjugate * gradient and insure symmetry. * - hypre_SMGRelax is the relaxation routine. There are different "data" * structures for each call to reflect different arguments and parameters. * One important parameter sets whether or not an initial guess of zero * is to be used in the relaxation. * - hypre_SMGResidual computes the residual, b - Ax. * - hypre_SemiRestrict restricts the residual to the coarse grid. * - hypre_SemiInterp interpolates the coarse error and adds it to the * fine grid solution. * *--------------------------------------------------------------------------*/ HYPRE_Int hypre_SMGSolve( void *smg_vdata, hypre_StructMatrix *A, hypre_StructVector *b, hypre_StructVector *x ) { hypre_SMGData *smg_data = smg_vdata; double tol = (smg_data -> tol); HYPRE_Int max_iter = (smg_data -> max_iter); HYPRE_Int rel_change = (smg_data -> rel_change); HYPRE_Int zero_guess = (smg_data -> zero_guess); HYPRE_Int num_levels = (smg_data -> num_levels); HYPRE_Int num_pre_relax = (smg_data -> num_pre_relax); HYPRE_Int num_post_relax = (smg_data -> num_post_relax); hypre_IndexRef base_index = (smg_data -> base_index); hypre_IndexRef base_stride = (smg_data -> base_stride); hypre_StructMatrix **A_l = (smg_data -> A_l); hypre_StructMatrix **PT_l = (smg_data -> PT_l); hypre_StructMatrix **R_l = (smg_data -> R_l); hypre_StructVector **b_l = (smg_data -> b_l); hypre_StructVector **x_l = (smg_data -> x_l); hypre_StructVector **r_l = (smg_data -> r_l); hypre_StructVector **e_l = (smg_data -> e_l); void **relax_data_l = (smg_data -> relax_data_l); void **residual_data_l = (smg_data -> residual_data_l); void **restrict_data_l = (smg_data -> restrict_data_l); void **interp_data_l = (smg_data -> interp_data_l); HYPRE_Int logging = (smg_data -> logging); double *norms = (smg_data -> norms); double *rel_norms = (smg_data -> rel_norms); double b_dot_b, r_dot_r, eps; double e_dot_e, x_dot_x; HYPRE_Int i, l; #if DEBUG char filename[255]; #endif /*----------------------------------------------------- * Initialize some things and deal with special cases *-----------------------------------------------------*/ hypre_BeginTiming(smg_data -> time_index); hypre_StructMatrixDestroy(A_l[0]); hypre_StructVectorDestroy(b_l[0]); hypre_StructVectorDestroy(x_l[0]); A_l[0] = hypre_StructMatrixRef(A); b_l[0] = hypre_StructVectorRef(b); x_l[0] = hypre_StructVectorRef(x); (smg_data -> num_iterations) = 0; /* if max_iter is zero, return */ if (max_iter == 0) { /* if using a zero initial guess, return zero */ if (zero_guess) { hypre_StructVectorSetConstantValues(x, 0.0); } hypre_EndTiming(smg_data -> time_index); return hypre_error_flag; } /* part of convergence check */ if (tol > 0.0) { /* eps = (tol^2) */ b_dot_b = hypre_StructInnerProd(b_l[0], b_l[0]); eps = tol*tol; /* if rhs is zero, return a zero solution */ if (b_dot_b == 0.0) { hypre_StructVectorSetConstantValues(x, 0.0); if (logging > 0) { norms[0] = 0.0; rel_norms[0] = 0.0; } hypre_EndTiming(smg_data -> time_index); return hypre_error_flag; } } /*----------------------------------------------------- * Do V-cycles: * For each index l, "fine" = l, "coarse" = (l+1) *-----------------------------------------------------*/ for (i = 0; i < max_iter; i++) { /*-------------------------------------------------- * Down cycle *--------------------------------------------------*/ /* fine grid pre-relaxation */ if (num_levels > 1) { hypre_SMGRelaxSetRegSpaceRank(relax_data_l[0], 0, 0); hypre_SMGRelaxSetRegSpaceRank(relax_data_l[0], 1, 1); } hypre_SMGRelaxSetMaxIter(relax_data_l[0], num_pre_relax); hypre_SMGRelaxSetZeroGuess(relax_data_l[0], zero_guess); hypre_SMGRelax(relax_data_l[0], A_l[0], b_l[0], x_l[0]); zero_guess = 0; /* compute fine grid residual (b - Ax) */ hypre_SMGResidual(residual_data_l[0], A_l[0], x_l[0], b_l[0], r_l[0]); /* convergence check */ if (tol > 0.0) { r_dot_r = hypre_StructInnerProd(r_l[0], r_l[0]); if (logging > 0) { norms[i] = sqrt(r_dot_r); if (b_dot_b > 0) rel_norms[i] = sqrt(r_dot_r/b_dot_b); else rel_norms[i] = 0.0; } /* always do at least 1 V-cycle */ if ((r_dot_r/b_dot_b < eps) && (i > 0)) { if (rel_change) { if ((e_dot_e/x_dot_x) < eps) break; } else { break; } } } if (num_levels > 1) { /* restrict fine grid residual */ hypre_SemiRestrict(restrict_data_l[0], R_l[0], r_l[0], b_l[1]); #if DEBUG if(hypre_StructStencilDim(hypre_StructMatrixStencil(A)) == 3) { hypre_sprintf(filename, "zout_xdown.%02d", 0); hypre_StructVectorPrint(filename, x_l[0], 0); hypre_sprintf(filename, "zout_rdown.%02d", 0); hypre_StructVectorPrint(filename, r_l[0], 0); hypre_sprintf(filename, "zout_b.%02d", 1); hypre_StructVectorPrint(filename, b_l[1], 0); } #endif for (l = 1; l <= (num_levels - 2); l++) { /* pre-relaxation */ hypre_SMGRelaxSetRegSpaceRank(relax_data_l[l], 0, 0); hypre_SMGRelaxSetRegSpaceRank(relax_data_l[l], 1, 1); hypre_SMGRelaxSetMaxIter(relax_data_l[l], num_pre_relax); hypre_SMGRelaxSetZeroGuess(relax_data_l[l], 1); hypre_SMGRelax(relax_data_l[l], A_l[l], b_l[l], x_l[l]); /* compute residual (b - Ax) */ hypre_SMGResidual(residual_data_l[l], A_l[l], x_l[l], b_l[l], r_l[l]); /* restrict residual */ hypre_SemiRestrict(restrict_data_l[l], R_l[l], r_l[l], b_l[l+1]); #if DEBUG if(hypre_StructStencilDim(hypre_StructMatrixStencil(A)) == 3) { hypre_sprintf(filename, "zout_xdown.%02d", l); hypre_StructVectorPrint(filename, x_l[l], 0); hypre_sprintf(filename, "zout_rdown.%02d", l); hypre_StructVectorPrint(filename, r_l[l], 0); hypre_sprintf(filename, "zout_b.%02d", l+1); hypre_StructVectorPrint(filename, b_l[l+1], 0); } #endif } /*-------------------------------------------------- * Bottom *--------------------------------------------------*/ hypre_SMGRelaxSetZeroGuess(relax_data_l[l], 1); hypre_SMGRelax(relax_data_l[l], A_l[l], b_l[l], x_l[l]); #if DEBUG if(hypre_StructStencilDim(hypre_StructMatrixStencil(A)) == 3) { hypre_sprintf(filename, "zout_xbottom.%02d", l); hypre_StructVectorPrint(filename, x_l[l], 0); } #endif /*-------------------------------------------------- * Up cycle *--------------------------------------------------*/ for (l = (num_levels - 2); l >= 1; l--) { /* interpolate error and correct (x = x + Pe_c) */ hypre_SemiInterp(interp_data_l[l], PT_l[l], x_l[l+1], e_l[l]); hypre_StructAxpy(1.0, e_l[l], x_l[l]); #if DEBUG if(hypre_StructStencilDim(hypre_StructMatrixStencil(A)) == 3) { hypre_sprintf(filename, "zout_eup.%02d", l); hypre_StructVectorPrint(filename, e_l[l], 0); hypre_sprintf(filename, "zout_xup.%02d", l); hypre_StructVectorPrint(filename, x_l[l], 0); } #endif /* post-relaxation */ hypre_SMGRelaxSetRegSpaceRank(relax_data_l[l], 0, 1); hypre_SMGRelaxSetRegSpaceRank(relax_data_l[l], 1, 0); hypre_SMGRelaxSetMaxIter(relax_data_l[l], num_post_relax); hypre_SMGRelaxSetZeroGuess(relax_data_l[l], 0); hypre_SMGRelax(relax_data_l[l], A_l[l], b_l[l], x_l[l]); } /* interpolate error and correct on fine grid (x = x + Pe_c) */ hypre_SemiInterp(interp_data_l[0], PT_l[0], x_l[1], e_l[0]); hypre_SMGAxpy(1.0, e_l[0], x_l[0], base_index, base_stride); #if DEBUG if(hypre_StructStencilDim(hypre_StructMatrixStencil(A)) == 3) { hypre_sprintf(filename, "zout_eup.%02d", 0); hypre_StructVectorPrint(filename, e_l[0], 0); hypre_sprintf(filename, "zout_xup.%02d", 0); hypre_StructVectorPrint(filename, x_l[0], 0); } #endif } /* part of convergence check */ if ((tol > 0.0) && (rel_change)) { if (num_levels > 1) { e_dot_e = hypre_StructInnerProd(e_l[0], e_l[0]); x_dot_x = hypre_StructInnerProd(x_l[0], x_l[0]); } else { e_dot_e = 0.0; x_dot_x = 1.0; } } /* fine grid post-relaxation */ if (num_levels > 1) { hypre_SMGRelaxSetRegSpaceRank(relax_data_l[0], 0, 1); hypre_SMGRelaxSetRegSpaceRank(relax_data_l[0], 1, 0); } hypre_SMGRelaxSetMaxIter(relax_data_l[0], num_post_relax); hypre_SMGRelaxSetZeroGuess(relax_data_l[0], 0); hypre_SMGRelax(relax_data_l[0], A_l[0], b_l[0], x_l[0]); (smg_data -> num_iterations) = (i + 1); } hypre_EndTiming(smg_data -> time_index); return hypre_error_flag; }