443 lines
12 KiB
C
443 lines
12 KiB
C
/*
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* Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
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* All rights reserved. This file is part of nusif-solver.
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* Use of this source code is governed by a MIT style
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* license that can be found in the LICENSE file.
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*/
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#include <math.h>
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#include <mpi.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "allocate.h"
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#include "parameter.h"
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#include "solver.h"
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#define PI 3.14159265358979323846
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#define P(i, j) p[(j) * (imax + 2) + (i)]
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#define RHS(i, j) rhs[(j) * (imax + 2) + (i)]
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static int sizeOfRank(int rank, int size, int N)
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{
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return N / size + ((N % size > rank) ? 1 : 0);
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}
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static void print(Solver* solver)
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{
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double* p = solver->p;
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int imax = solver->imax;
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printf("### RANK %d #######################################################\n",
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solver->rank);
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for (int j = 0; j < solver->jmaxLocal + 2; j++) {
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printf("%02d: ", j);
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for (int i = 0; i < solver->imax + 2; i++) {
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printf("%12.8f ", P(i, j));
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}
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printf("\n");
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}
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fflush(stdout);
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}
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static void exchange(Solver* solver)
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{
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MPI_Request requests[4] = { MPI_REQUEST_NULL,
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MPI_REQUEST_NULL,
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MPI_REQUEST_NULL,
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MPI_REQUEST_NULL };
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/* exchange ghost cells with top neighbor */
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if (solver->rank + 1 < solver->size) {
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int top = solver->rank + 1;
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double* src = solver->p + (solver->jmaxLocal) * (solver->imax + 2) + 1;
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double* dst = solver->p + (solver->jmaxLocal + 1) * (solver->imax + 2) + 1;
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MPI_Isend(src, solver->imax, MPI_DOUBLE, top, 1, MPI_COMM_WORLD, &requests[0]);
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MPI_Irecv(dst, solver->imax, MPI_DOUBLE, top, 2, MPI_COMM_WORLD, &requests[1]);
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}
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/* exchange ghost cells with bottom neighbor */
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if (solver->rank > 0) {
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int bottom = solver->rank - 1;
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double* src = solver->p + (solver->imax + 2) + 1;
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double* dst = solver->p + 1;
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MPI_Isend(src, solver->imax, MPI_DOUBLE, bottom, 2, MPI_COMM_WORLD, &requests[2]);
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MPI_Irecv(dst, solver->imax, MPI_DOUBLE, bottom, 1, MPI_COMM_WORLD, &requests[3]);
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}
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MPI_Waitall(4, requests, MPI_STATUSES_IGNORE);
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}
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void getResult(Solver* solver)
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{
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double* Pall = NULL;
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int *rcvCounts, *displs;
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if (solver->rank == 0) {
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Pall = allocate(64, (solver->imax + 2) * (solver->jmax + 2) * sizeof(double));
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rcvCounts = (int*)malloc(solver->size * sizeof(int));
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displs = (int*)malloc(solver->size * sizeof(int));
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rcvCounts[0] = solver->jmaxLocal * (solver->imax + 2);
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displs[0] = 0;
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int cursor = rcvCounts[0];
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for (int i = 1; i < solver->size; i++) {
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rcvCounts[i] = sizeOfRank(i, solver->size, solver->jmax) * (solver->imax + 2);
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displs[i] = cursor;
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cursor += rcvCounts[i];
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}
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}
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int cnt = solver->jmaxLocal * (solver->imax + 2);
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double* sendbuffer = solver->p + (solver->imax + 2);
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MPI_Gatherv(sendbuffer,
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cnt,
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MPI_DOUBLE,
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Pall,
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rcvCounts,
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displs,
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MPI_DOUBLE,
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0,
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MPI_COMM_WORLD);
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if (solver->rank == 0) {
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writeResult(solver, Pall, "p.dat");
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}
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}
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void initSolver(Solver* solver, Parameter* params, int problem)
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{
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MPI_Comm_rank(MPI_COMM_WORLD, &(solver->rank));
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MPI_Comm_size(MPI_COMM_WORLD, &(solver->size));
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solver->imax = params->imax;
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solver->jmax = params->jmax;
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solver->jmaxLocal = sizeOfRank(solver->rank, solver->size, solver->jmax);
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printf("RANK %d: imaxLocal : %d, jmaxLocal : %d\n",
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solver->rank,
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solver->imax,
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solver->jmaxLocal);
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solver->dx = params->xlength / params->imax;
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solver->dy = params->ylength / params->jmax;
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solver->ys = solver->rank * solver->jmaxLocal * solver->dy;
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solver->eps = params->eps;
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solver->omega = params->omg;
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solver->itermax = params->itermax;
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int imax = solver->imax;
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int jmax = solver->jmax;
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int jmaxLocal = solver->jmaxLocal;
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solver->p = allocate(64, (imax + 2) * (jmaxLocal + 2) * sizeof(double));
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solver->rhs = allocate(64, (imax + 2) * (jmax + 2) * sizeof(double));
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double dx = solver->dx;
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double dy = solver->dy;
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double* p = solver->p;
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double* rhs = solver->rhs;
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for (int j = 0; j < jmaxLocal + 2; j++) {
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double y = solver->ys + j * dy;
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for (int i = 0; i < imax + 2; i++) {
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P(i, j) = sin(4.0 * PI * i * dx) + sin(4.0 * PI * y);
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}
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}
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if (problem == 2) {
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for (int j = 0; j < jmax + 2; j++) {
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for (int i = 0; i < imax + 2; i++) {
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RHS(i, j) = sin(2.0 * PI * i * dx);
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}
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}
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} else {
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for (int j = 0; j < jmax + 2; j++) {
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for (int i = 0; i < imax + 2; i++) {
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RHS(i, j) = 0.0;
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}
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}
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}
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}
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void debug(Solver* solver)
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{
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int imax = solver->imax;
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int rank = solver->rank;
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double* p = solver->p;
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/* for( int j=0; j < solver->jmaxLocal+2; j++ ) { */
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/* for( int i=0; i < solver->imax+2; i++ ) { */
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/* P(i, j) = (double) rank; */
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/* } */
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/* } */
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/* for ( int i=0; i < solver->size; i++) { */
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/* if ( i == rank ) { */
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/* print(solver); */
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/* } */
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/* MPI_Barrier(MPI_COMM_WORLD); */
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/* } */
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/* if ( rank == 0 ) { */
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/* printf("##########################################################\n"); */
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/* printf("## Exchange ghost layers\n"); */
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/* printf("##########################################################\n"); */
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/* } */
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/* exchange(solver); */
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for (int i = 0; i < solver->size; i++) {
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if (i == rank) {
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print(solver);
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}
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MPI_Barrier(MPI_COMM_WORLD);
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}
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}
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int solve(Solver* solver)
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{
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double r;
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int it = 0;
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double res, res1;
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int imax = solver->imax;
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int jmax = solver->jmax;
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int jmaxLocal = solver->jmaxLocal;
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double eps = solver->eps;
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double omega = solver->omega;
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int itermax = solver->itermax;
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double dx2 = solver->dx * solver->dx;
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double dy2 = solver->dy * solver->dy;
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double idx2 = 1.0 / dx2;
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double idy2 = 1.0 / dy2;
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double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
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double* p = solver->p;
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double* rhs = solver->rhs;
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double epssq = eps * eps;
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res = eps + 1.0;
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while ((res >= epssq) && (it < itermax)) {
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res = 0.0;
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exchange(solver);
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for (int j = 1; j < jmaxLocal + 1; j++) {
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for (int i = 1; i < imax + 1; i++) {
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r = RHS(i, j) - ((P(i - 1, j) - 2.0 * P(i, j) + P(i + 1, j)) * idx2 +
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(P(i, j - 1) - 2.0 * P(i, j) + P(i, j + 1)) * idy2);
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P(i, j) -= (factor * r);
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res += (r * r);
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}
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}
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if (solver->rank == 0) {
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for (int i = 1; i < imax + 1; i++) {
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P(i, 0) = P(i, 1);
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}
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}
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if (solver->rank == (solver->size - 1)) {
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for (int i = 1; i < imax + 1; i++) {
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P(i, jmaxLocal + 1) = P(i, jmaxLocal);
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}
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}
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for (int j = 1; j < jmaxLocal + 1; j++) {
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P(0, j) = P(1, j);
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P(imax + 1, j) = P(imax, j);
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}
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MPI_Allreduce(&res, &res1, 1, MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
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res = res1;
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res = sqrt(res / (imax * jmax));
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#ifdef DEBUG
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if (solver->rank == 0) {
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printf("%d Residuum: %e\n", it, res1);
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}
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#endif
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it++;
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}
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if (solver->rank == 0) {
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printf("Solver took %d iterations\n", it);
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}
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if (res < eps) {
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return 1;
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} else {
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return 0;
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}
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}
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int solveRB(Solver* solver)
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{
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double r;
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int it = 0;
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double res, res1;
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int imax = solver->imax;
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int jmax = solver->jmax;
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int jmaxLocal = solver->jmaxLocal;
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double eps = solver->eps;
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double omega = solver->omega;
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int itermax = solver->itermax;
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double dx2 = solver->dx * solver->dx;
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double dy2 = solver->dy * solver->dy;
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double idx2 = 1.0 / dx2;
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double idy2 = 1.0 / dy2;
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double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
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double* p = solver->p;
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double* rhs = solver->rhs;
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int pass, jsw, isw;
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double epssq = eps * eps;
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res = eps + 1.0;
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while ((res >= epssq) && (it < itermax)) {
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res = 0.0;
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jsw = 1;
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for (pass = 0; pass < 2; pass++) {
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isw = jsw;
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exchange(solver);
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for (int j = 1; j < jmaxLocal + 1; j++) {
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for (int i = isw; i < imax + 1; i += 2) {
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double r = RHS(i, j) -
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((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
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P(i, j) -= (factor * r);
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res += (r * r);
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}
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isw = 3 - isw;
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}
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jsw = 3 - jsw;
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}
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for (int i = 1; i < imax + 1; i++) {
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P(i, 0) = P(i, 1);
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P(i, jmaxLocal + 1) = P(i, jmaxLocal);
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}
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for (int j = 1; j < jmaxLocal + 1; j++) {
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P(0, j) = P(1, j);
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P(imax + 1, j) = P(imax, j);
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}
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MPI_Allreduce(&res, &res1, 1, MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
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res = res1;
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res = res / (double)(imax * jmax);
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#ifdef DEBUG
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printf("%d Residuum: %e\n", it, res);
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#endif
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it++;
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}
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if (solver->rank == 0) {
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printf("Solver took %d iterations\n", it);
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}
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if (res < eps) {
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return 1;
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} else {
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return 0;
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}
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}
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int solveRBA(Solver* solver)
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{
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double r;
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int it = 0;
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double res;
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int imax = solver->imax;
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int jmax = solver->jmax;
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int jmaxLocal = solver->jmaxLocal;
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double eps = solver->eps;
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double omega = solver->omega;
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int itermax = solver->itermax;
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double dx2 = solver->dx * solver->dx;
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double dy2 = solver->dy * solver->dy;
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double idx2 = 1.0 / dx2;
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double idy2 = 1.0 / dy2;
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double factor = omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
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double* p = solver->p;
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double* rhs = solver->rhs;
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int pass, jsw, isw;
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double rho = solver->rho;
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double epssq = eps * eps;
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res = eps + 1.0;
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while ((res >= epssq) && (it < itermax)) {
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res = 0.0;
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jsw = 1;
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for (pass = 0; pass < 2; pass++) {
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isw = jsw;
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exchange(solver);
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for (int j = 1; j < jmaxLocal + 1; j++) {
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for (int i = isw; i < imax + 1; i += 2) {
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double r = RHS(i, j) -
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((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
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P(i, j) -= (omega * factor * r);
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res += (r * r);
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}
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isw = 3 - isw;
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}
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jsw = 3 - jsw;
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omega = (it == 0 && pass == 0 ? 1.0 / (1.0 - 0.5 * rho * rho)
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: 1.0 / (1.0 - 0.25 * rho * rho * omega));
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}
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for (int i = 1; i < imax + 1; i++) {
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P(i, 0) = P(i, 1);
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P(i, jmaxLocal + 1) = P(i, jmaxLocal);
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}
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for (int j = 1; j < jmaxLocal + 1; j++) {
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P(0, j) = P(1, j);
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P(imax + 1, j) = P(imax, j);
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}
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res = res / (double)(imax * jmax);
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#ifdef DEBUG
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printf("%d Residuum: %e Omega: %e\n", it, res, omega);
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#endif
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it++;
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}
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printf("Final omega: %f\n", omega);
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printf("Solver took %d iterations to reach %f\n", it, sqrt(res));
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}
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void writeResult(Solver* solver, double* m, char* filename)
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{
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int imax = solver->imax;
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int jmax = solver->jmax;
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double* p = solver->p;
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FILE* fp;
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fp = fopen(filename, "w");
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if (fp == NULL) {
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printf("Error!\n");
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exit(EXIT_FAILURE);
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}
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for (int j = 0; j < jmax + 2; j++) {
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for (int i = 0; i < imax + 2; i++) {
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fprintf(fp, "%f ", m[j * (imax + 2) + i]);
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}
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fprintf(fp, "\n");
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}
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fclose(fp);
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}
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