diff options
author | Anton Khirnov <anton@khirnov.net> | 2019-01-29 15:38:17 +0100 |
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committer | Anton Khirnov <anton@khirnov.net> | 2019-01-29 15:38:17 +0100 |
commit | 40e686b7688345a903f4afb97362de7d57cbb3c7 (patch) | |
tree | e28466537988295de240e6c1aac4b96e35880a6b /mg2d.c | |
parent | 2d00e4bf8b63bbe1c4442cd7f765ef8782f5ac6c (diff) |
mg2d: account for effect of the ~u term on the relaxation factor
The maximum allowed time step in the presence of a -K * u term goes like
2 (dx ** 2) / (4 + K (dx ** 2))
Diffstat (limited to 'mg2d.c')
-rw-r--r-- | mg2d.c | 20 |
1 files changed, 20 insertions, 0 deletions
@@ -64,6 +64,8 @@ struct MG2DInternal { int cpuflags; + double fac00_max; + int64_t time_solve; int64_t count_solve; }; @@ -407,11 +409,26 @@ static void restrict_diff_coeffs(MG2DContext *ctx, MG2DLevel *dst, MG2DLevel *sr } } +static double findmax(double *arr, size_t size[2], ptrdiff_t stride) +{ + double ret = 0.0; + for (size_t y = 0; y < size[1]; y++) + for (size_t x = 0; x < size[0]; x++) { + double val = fabs(arr[y * stride + x]); + if (val > ret) + ret = val; + } + return ret; +} + static int mg_levels_init(MG2DContext *ctx) { MG2DInternal *priv = ctx->priv; MG2DLevel *cur, *prev; + priv->fac00_max = findmax(ctx->diff_coeffs[MG2D_DIFF_COEFF_00], priv->root->solver->domain_size, + ctx->diff_coeffs_stride); + cur = priv->root; prev = NULL; while (cur) { @@ -454,6 +471,9 @@ static int mg_levels_init(MG2DContext *ctx) if (cur->solver->solver_type == EGS_SOLVER_RELAXATION) { EGSRelaxContext *r = cur->solver->solver_data; r->relax_factor = ctx->cfl_factor; + + r->relax_multiplier = 1.0 / (1.0 + cur->solver->step[0] * cur->solver->step[1] * + priv->fac00_max / 8.0); } prev = cur; |