From ebb534676acce17c81c92ac7fe461f01830f95d2 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <matthieu.schaller@durham.ac.uk>
Date: Fri, 21 Apr 2017 14:34:45 +0100
Subject: [PATCH] Record r_max and CoM of each multipole at rebuild time.
---
src/multipole.h | 32 ++++++++++++++++++++++++++++++++
src/runner.c | 3 +--
src/runner_doiact_grav.h | 4 ++--
src/space.c | 8 ++++++++
4 files changed, 43 insertions(+), 4 deletions(-)
diff --git a/src/multipole.h b/src/multipole.h
index 48be0a31dd..15f9371fa2 100644
--- a/src/multipole.h
+++ b/src/multipole.h
@@ -176,9 +176,15 @@ struct gravity_tensors {
/*! Centre of mass of the matter dsitribution */
double CoM[3];
+ /*! Centre of mass of the matter dsitribution at the last rebuild */
+ double CoM_rebuild[3];
+
/*! Upper limit of the CoM<->gpart distance */
double r_max;
+ /*! Upper limit of the CoM<->gpart distance at the last rebuild */
+ double r_max_rebuild;
+
/*! Multipole mass */
struct multipole m_pole;
@@ -2537,4 +2543,30 @@ __attribute__((always_inline)) INLINE static int gravity_multipole_accept(
return (r2 > (r_crit_a + r_crit_b) * (r_crit_a + r_crit_b));
}
+/**
+ * @brief Checks whether a cell-cell interaction can be appromixated by a M-M
+ * interaction using the r_max at rebuild time.
+ *
+ * @param ma The #multipole of the first #cell.
+ * @param mb The #multipole of the second #cell.
+ * @param theta_crit_inv The inverse of the critical opening angle.
+ */
+__attribute__((always_inline)) INLINE static int
+gravity_multipole_accept_rebuild(const struct gravity_tensors *ma,
+ const struct gravity_tensors *mb,
+ double theta_crit_inv) {
+
+ const double r_crit_a = ma->r_max_rebuild * theta_crit_inv;
+ const double r_crit_b = mb->r_max_rebuild * theta_crit_inv;
+
+ const double dx = ma->CoM_rebuild[0] - mb->CoM_rebuild[0];
+ const double dy = ma->CoM_rebuild[1] - mb->CoM_rebuild[1];
+ const double dz = ma->CoM_rebuild[2] - mb->CoM_rebuild[2];
+
+ const double r2 = dx * dx + dy * dy + dz * dz;
+
+ /* Multipole acceptance criterion (Dehnen 2002, eq.10) */
+ return (r2 > (r_crit_a + r_crit_b) * (r_crit_a + r_crit_b));
+}
+
#endif /* SWIFT_MULTIPOLE_H */
diff --git a/src/runner.c b/src/runner.c
index 18e48c945d..512a4f362f 100644
--- a/src/runner.c
+++ b/src/runner.c
@@ -1392,8 +1392,7 @@ void runner_do_end_force(struct runner *r, struct cell *c, int timer) {
if (e->policy & engine_policy_self_gravity) {
/* Check that this gpart has interacted with all the other
- * particles
- * (via direct or multipoles) in the box */
+ * particles (via direct or multipoles) in the box */
gp->num_interacted++;
if (gp->num_interacted != (long long)e->s->nr_gparts)
error(
diff --git a/src/runner_doiact_grav.h b/src/runner_doiact_grav.h
index 8161a13e76..d35e100ec6 100644
--- a/src/runner_doiact_grav.h
+++ b/src/runner_doiact_grav.h
@@ -638,8 +638,8 @@ void runner_do_grav_long_range(struct runner *r, struct cell *ci, int timer) {
if (ci == cj || cj->gcount == 0) continue;
/* Check the multipole acceptance criterion */
- if (gravity_multipole_accept(ci->multipole, cj->multipole,
- theta_crit_inv)) {
+ if (gravity_multipole_accept_rebuild(ci->multipole, cj->multipole,
+ theta_crit_inv)) {
/* Go for a (non-symmetric) M-M calculation */
runner_dopair_grav_mm(r, ci, cj);
}
diff --git a/src/space.c b/src/space.c
index 7b59be248d..8e5c6ba15a 100644
--- a/src/space.c
+++ b/src/space.c
@@ -2115,6 +2115,10 @@ void space_split_recursive(struct space *s, struct cell *c,
/* Take minimum of both limits */
c->multipole->r_max = min(r_max, sqrt(dx * dx + dy * dy + dz * dz));
+ c->multipole->r_max_rebuild = c->multipole->r_max;
+ c->multipole->CoM_rebuild[0] = c->multipole->CoM[0];
+ c->multipole->CoM_rebuild[1] = c->multipole->CoM[1];
+ c->multipole->CoM_rebuild[2] = c->multipole->CoM[2];
} /* Deal with gravity */
}
@@ -2194,6 +2198,10 @@ void space_split_recursive(struct space *s, struct cell *c,
c->multipole->r_max = 0.;
}
}
+ c->multipole->r_max_rebuild = c->multipole->r_max;
+ c->multipole->CoM_rebuild[0] = c->multipole->CoM[0];
+ c->multipole->CoM_rebuild[1] = c->multipole->CoM[1];
+ c->multipole->CoM_rebuild[2] = c->multipole->CoM[2];
}
/* Set the values for this cell. */
--
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