From 362d83d36de4147554a57b7adf5b5aa3fabc4a58 Mon Sep 17 00:00:00 2001
From: Jacob Kegerreis <jacob.kegerreis@durham.ac.uk>
Date: Thu, 23 Jul 2020 19:21:16 +0100
Subject: [PATCH] Tidy and fix the geometric criterion for making gravity
proxies
---
src/engine.c | 34 ++++++++++++++--------------------
src/engine.h | 1 -
2 files changed, 14 insertions(+), 21 deletions(-)
diff --git a/src/engine.c b/src/engine.c
index 2786a62a5d..6f877d2920 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -3172,11 +3172,8 @@ void engine_makeproxies(struct engine *e) {
cell_width[2] * cell_width[2];
const double r_diag = 0.5 * sqrt(r_diag2);
- /* Maximal distance from a shifted CoM to centre of cell */
- const double delta_CoM = engine_max_proxy_centre_frac * r_diag;
-
/* Maximal distance from shifted CoM to any corner */
- const double r_max = r_diag + 2. * delta_CoM;
+ const double r_max = 2 * r_diag;
/* Prepare the proxies and the proxy index. */
if (e->proxy_ind == NULL)
@@ -3240,7 +3237,7 @@ void engine_makeproxies(struct engine *e) {
/* Get the cell ID. */
const int cjd = cell_getid(cdim, iii, jjj, kkk);
-
+
/* Early abort */
if (cid >= cjd) continue;
@@ -3289,35 +3286,32 @@ void engine_makeproxies(struct engine *e) {
proxy_type |= (int)proxy_cell_type_gravity;
} else {
- /* We don't have multipoles yet (or there CoMs) so we will
+ /* We don't have multipoles yet (or their CoMs) so we will
have to cook up something based on cell locations only. We
- hence need an upper limit on the distance that the CoMs in
- those cells could have. We then can decide whether we are
- too close for an M2L interaction and hence require a proxy
- as this pair of cells cannot rely on just an M2L
- calculation. */
+ hence need a lower limit on the distance that the CoMs in
+ those cells could have and an upper limit on the distance
+ of the furthest particle in the multipole from its CoM.
+ We then can decide whether we are too close for an M2L
+ interaction and hence require a proxy as this pair of cells
+ cannot rely on just an M2L calculation. */
/* Minimal distance between any two points in the cells */
- const double min_dist_centres2 = cell_min_dist2_same_size(
+ const double min_dist_CoM2 = cell_min_dist2_same_size(
&cells[cid], &cells[cjd], periodic, dim);
- /* Let's now assume the CoMs will shift a bit */
- const double min_dist_CoM =
- sqrt(min_dist_centres2) - 2. * delta_CoM;
- const double min_dist_CoM2 = min_dist_CoM * min_dist_CoM;
-
/* Are we beyond the distance where the truncated forces are 0
* but not too far such that M2L can be used? */
if (periodic) {
if ((min_dist_CoM2 < max_mesh_dist2) &&
- !(2. * r_max < theta_crit * min_dist_CoM2))
+ !(4. * r_max * r_max < theta_crit * theta_crit * min_dist_CoM2))
proxy_type |= (int)proxy_cell_type_gravity;
} else {
- if (!(2. * r_max < theta_crit * min_dist_CoM2))
- proxy_type |= (int)proxy_cell_type_gravity;
+ if (!(4. * r_max * r_max < theta_crit * theta_crit * min_dist_CoM2)){
+ proxy_type |= (int)proxy_cell_type_gravity;
+ }
}
}
}
diff --git a/src/engine.h b/src/engine.h
index 8dc34ad96d..dd41b72ded 100644
--- a/src/engine.h
+++ b/src/engine.h
@@ -107,7 +107,6 @@ enum engine_step_properties {
#define engine_maxproxies 64
#define engine_tasksreweight 1
#define engine_parts_size_grow 1.05
-#define engine_max_proxy_centre_frac 1
#define engine_redistribute_alloc_margin 1.2
#define engine_rebuild_link_alloc_margin 1.2
#define engine_foreign_alloc_margin 1.05
--
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