Time-stepping conditions extracted from the code.

src/timestep.h

+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Coypright (c) 2015 Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
+/**
+ * @brief Computes the hydro time-step of a given particle
+ *
+ * @param p Pointer to the particle data
+ * @param xp Pointer to the extended particle data
+ *
+ */
+__attribute__((always_inline)) INLINE static float compute_timestep_hydro(
+    struct part* p, struct xpart* xp) {
+
+  /* CFL condition */
+  float dt_cfl = const_cfl * p->h / p->force.v_sig;
+
+  /* Limit change in h */
+  float dt_h_change = (p->force.h_dt != 0.0f)
+                          ? fabsf(const_ln_max_h_change * p->h / p->force.h_dt)
+                          : FLT_MAX;
+
+  /* Limit change in u */
+  float dt_u_change = (p->force.u_dt != 0.0f)
+                          ? fabsf(const_max_u_change * p->u / p->force.u_dt)
+                          : FLT_MAX;
+
+  return fminf(dt_cfl, fminf(dt_h_change, dt_u_change));
+}
+
+/**
+ * @brief Computes the gravity time-step of a given particle
+ *
+ * @param p Pointer to the particle data
+ * @param xp Pointer to the extended particle data
+ *
+ */
+
+__attribute__((always_inline)) INLINE static float compute_timestep_grav(
+    struct part* p, struct xpart* xp) {
+
+  /* Currently no limit is imposed */
+  return FLT_MAX;
+}