From 99cd43b5c824309961a0dae2782704b73b02e881 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Fri, 28 Dec 2018 10:15:39 +0100 Subject: Add test programs for relaxation and full multigrid. --- mg2d_test.c | 184 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 184 insertions(+) create mode 100644 mg2d_test.c (limited to 'mg2d_test.c') diff --git a/mg2d_test.c b/mg2d_test.c new file mode 100644 index 0000000..9b55963 --- /dev/null +++ b/mg2d_test.c @@ -0,0 +1,184 @@ +#include +#include +#include +#include +#include + +#include "mg2d.h" + +#define MAXITER 64 +#define TOL 1e-9 + +#if 1 +static double sol(double x, double y) +{ + return sin(M_PI * x) * sin(M_PI * y); +} +static double sol_dx(double x, double y) +{ + return M_PI * cos(M_PI * x) * sin(M_PI * y); +} +static double sol_dy(double x, double y) +{ + return M_PI * sin(M_PI * x) * cos(M_PI * y); +} +static double sol_dxx(double x, double y) +{ + return -M_PI * M_PI * sol(x, y); +} +static double sol_dyy(double x, double y) +{ + return -M_PI * M_PI * sol(x, y); +} +static double sol_dxy(double x, double y) +{ + return M_PI * M_PI * cos(M_PI * x) * cos(M_PI * y); +} +#endif + +int main(int argc, char **argv) +{ + MG2DContext *ctx; + long int gridsize; + int ret = 0; + + if (argc < 2) { + fprintf(stderr, "Usage: %s \n", argv[0]); + return 1; + } + gridsize = strtol(argv[1], NULL, 0); + if (gridsize <= 0) { + fprintf(stderr, "Invalid parameters: %ld\n", gridsize); + return 1; + } + + ctx = mg2d_solver_alloc(gridsize); + if (!ctx) { + fprintf(stderr, "Error allocating the solver context\n"); + return 1; + } + + ctx->step[0] = 1.0 / (gridsize - 1); + ctx->step[1] = 1.0 / (gridsize - 1); + + ctx->fd_stencil = 2; + + ctx->maxiter = MAXITER; + ctx->nb_relax_pre = 2; + ctx->nb_cycles = 1; + ctx->nb_relax_post = 2; + ctx->tol = TOL; + ctx->nb_threads = 1; + + { + MG2DBoundary *bnd = ctx->boundaries[MG2D_BOUNDARY_0L]; + + bnd->type = MG2D_BC_TYPE_FIXVAL; + + memset(bnd->val, 0, gridsize * sizeof(*bnd->val)); + + for (int j = 1; j < ctx->fd_stencil; j++) { + double *dst = bnd->val + j * bnd->val_stride; + + for (ptrdiff_t k = -j; k < (ptrdiff_t)ctx->domain_size + j; k++) + dst[k] = sol(-j * ctx->step[0], k * ctx->step[1]); + } + } + { + MG2DBoundary *bnd = ctx->boundaries[MG2D_BOUNDARY_0U]; + + bnd->type = MG2D_BC_TYPE_FIXVAL; + + memset(bnd->val, 0, gridsize * sizeof(*bnd->val)); + + for (int j = 1; j < ctx->fd_stencil; j++) { + double *dst = bnd->val + j * bnd->val_stride; + + for (ptrdiff_t k = -j; k < (ptrdiff_t)ctx->domain_size + j; k++) + dst[k] = sol((gridsize - 1 + j) * ctx->step[0], k * ctx->step[1]); + } + } + { + MG2DBoundary *bnd = ctx->boundaries[MG2D_BOUNDARY_1L]; + + bnd->type = MG2D_BC_TYPE_FIXVAL; + + memset(bnd->val, 0, gridsize * sizeof(*bnd->val)); + + for (int j = 1; j < ctx->fd_stencil; j++) { + double *dst = bnd->val + j * bnd->val_stride; + + for (ptrdiff_t k = -j; k < (ptrdiff_t)ctx->domain_size + j; k++) + dst[k] = sol(k * ctx->step[0], -j * ctx->step[1]); + } + } + { + MG2DBoundary *bnd = ctx->boundaries[MG2D_BOUNDARY_1U]; + + bnd->type = MG2D_BC_TYPE_FIXVAL; + + memset(bnd->val, 0, gridsize * sizeof(*bnd->val)); + + for (int j = 1; j < ctx->fd_stencil; j++) { + double *dst = bnd->val + j * bnd->val_stride; + + for (ptrdiff_t k = -j; k < (ptrdiff_t)ctx->domain_size + j; k++) + dst[k] = sol(k * ctx->step[0], (gridsize - 1 + j) * ctx->step[1]); + } + } + + + for (size_t y = 0; y < ctx->domain_size; y++) { + const double y_coord = y * ctx->step[1]; + + memset(ctx->u + y * ctx->u_stride, 0, sizeof(*ctx->u) * ctx->domain_size); + //memset(ctx->rhs + y * ctx->rhs_stride, 0, sizeof(*ctx->rhs) * ctx->domain_size[0]); + + for (size_t x = 0; x < ctx->domain_size; x++) { + const double x_coord = x * ctx->step[0]; + + ctx->diff_coeffs[MG2D_DIFF_COEFF_02][ctx->diff_coeffs_stride * y + x] = 1.0; + ctx->diff_coeffs[MG2D_DIFF_COEFF_20][ctx->diff_coeffs_stride * y + x] = 1.0; + ctx->diff_coeffs[MG2D_DIFF_COEFF_11][ctx->diff_coeffs_stride * y + x] = 1.0; + //ctx->diff_coeffs[ELL_RELAX_DIFF_COEFF_00][ctx->diff_coeffs_stride * y + x] = 2.0 * M_PI; + + ctx->rhs[y * ctx->rhs_stride + x] = sol_dxx(x_coord, y_coord) + sol_dyy(x_coord, y_coord) + sol_dxy(x_coord, y_coord); + } + memset(ctx->diff_coeffs[MG2D_DIFF_COEFF_00] + y * ctx->diff_coeffs_stride, 0, + sizeof(*ctx->diff_coeffs[0]) * ctx->domain_size); + memset(ctx->diff_coeffs[MG2D_DIFF_COEFF_01] + y * ctx->diff_coeffs_stride, 0, + sizeof(*ctx->diff_coeffs[0]) * ctx->domain_size); + memset(ctx->diff_coeffs[MG2D_DIFF_COEFF_10] + y * ctx->diff_coeffs_stride, 0, + sizeof(*ctx->diff_coeffs[0]) * ctx->domain_size); + } + + ret = mg2d_solve(ctx); + if (ret < 0) { + fprintf(stderr, "Error solving the equation\n"); + ret = 1; + goto fail; + } + + mg2d_print_stats(ctx, NULL); + + { + double max_err = 0.0; + + for (size_t y = 0; y < ctx->domain_size; y++) { + const double y_coord = y * ctx->step[1]; + + for (size_t x = 0; x < ctx->domain_size; x++) { + const double x_coord = x * ctx->step[0]; + double err = fabs(ctx->u[y * ctx->u_stride + x] - sol(x_coord, y_coord)); + if (err > max_err) + max_err = err; + } + } + fprintf(stderr, "max(|solution - exact|): %g\n", max_err); + fprintf(stdout, "%ld %g\n", gridsize, max_err); + } + +fail: + mg2d_solver_free(&ctx); + return ret; +} -- cgit v1.2.3