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))

1 files changed, 3 insertions, 0 deletions

diff --git a/ell_grid_solve.c b/ell_grid_solve.c
index 370deab..20de6bc 100644
--- a/ell_grid_solve.c
+++ b/ell_grid_solve.c
@@ -751,6 +751,9 @@ int mg2di_egs_init(EGSContext *ctx)
         else
             priv->r.relax_factor = r->relax_factor;
         priv->r.relax_factor *= ctx->step[0] * ctx->step[0];
+
+        if (r->relax_multiplier > 0.0)
+            priv->r.relax_factor *= r->relax_multiplier;
     }
 
     priv->fd_factors[MG2D_DIFF_COEFF_00] = 1.0 /  fd_denoms[ctx->fd_stencil - 1][MG2D_DIFF_COEFF_00];