Read in the new MAC parameters

examples/parameter_example.yml

@@ -62,20 +62,22 @@ Stars:
 
 # Parameters for the self-gravity scheme
 Gravity:
-  mesh_side_length:              128       # Number of cells along each axis for the periodic gravity mesh.
-  eta:                           0.025     # Constant dimensionless multiplier for time integration.
-  theta:                         0.7       # Opening angle (Multipole acceptance criterion).
-  comoving_DM_softening:         0.0026994 # Comoving Plummer-equivalent softening length for DM particles (in internal units).
-  max_physical_DM_softening:     0.0007    # Maximal Plummer-equivalent softening length in physical coordinates for DM particles (in internal units).
-  comoving_baryon_softening:     0.0026994 # Comoving Plummer-equivalent softening length for baryon particles (in internal units).
-  max_physical_baryon_softening: 0.0007    # Maximal Plummer-equivalent softening length in physical coordinates for baryon particles (in internal units).
-  softening_ratio_background:    0.04      # Fraction of the mean inter-particle separation to use as Plummer-equivalent softening for the background DM particles.
-  rebuild_frequency:             0.01      # (Optional) Frequency of the gravity-tree rebuild in units of the number of g-particles (this is the default value).
-  a_smooth:                      1.25      # (Optional) Smoothing scale in top-level cell sizes to smooth the long-range forces over (this is the default value).
-  r_cut_max:                     4.5       # (Optional) Cut-off in number of top-level cells beyond which no FMM forces are computed (this is the default value).
-  r_cut_min:                     0.1       # (Optional) Cut-off in number of top-level cells below which no truncation of FMM forces are performed (this is the default value).
-  dithering:                     1         # (Optional) Activate the dithering of the gravity mesh at every rebuild (this is the default value).
-  dithering_ratio:               1.0       # (Optional) Magnitude of each component of the dithering vector in units of the top-level cell sizes (this is the default value).
+  mesh_side_length:               128       # Number of cells along each axis for the periodic gravity mesh.
+  eta:                            0.025     # Constant dimensionless multiplier for time integration.
+  mulitpole_acceptance_criterion: adaptive  # Choice of mulitpole acceptance criterion: 'adaptive' OR 'geometric'.
+  epsilon_fmm:                    0.01      # Tolerance parameter for the adaptice multipole acceptance criterion.
+  theta_cr:                       0.7       # Opening angle for the purely gemoetric criterion.
+  comoving_DM_softening:          0.0026994 # Comoving Plummer-equivalent softening length for DM particles (in internal units).
+  max_physical_DM_softening:      0.0007    # Maximal Plummer-equivalent softening length in physical coordinates for DM particles (in internal units).
+  comoving_baryon_softening:      0.0026994 # Comoving Plummer-equivalent softening length for baryon particles (in internal units).
+  max_physical_baryon_softening:  0.0007    # Maximal Plummer-equivalent softening length in physical coordinates for baryon particles (in internal units).
+  softening_ratio_background:     0.04      # Fraction of the mean inter-particle separation to use as Plummer-equivalent softening for the background DM particles.
+  rebuild_frequency:              0.01      # (Optional) Frequency of the gravity-tree rebuild in units of the number of g-particles (this is the default value).
+  a_smooth:                       1.25      # (Optional) Smoothing scale in top-level cell sizes to smooth the long-range forces over (this is the default value).
+  r_cut_max:                      4.5       # (Optional) Cut-off in number of top-level cells beyond which no FMM forces are computed (this is the default value).
+  r_cut_min:                      0.1       # (Optional) Cut-off in number of top-level cells below which no truncation of FMM forces are performed (this is the default value).
+  dithering:                      1         # (Optional) Activate the dithering of the gravity mesh at every rebuild (this is the default value).
+  dithering_ratio:                1.0       # (Optional) Magnitude of each component of the dithering vector in units of the top-level cell sizes (this is the default value).
 
 # Parameters when running with SWIFT_GRAVITY_FORCE_CHECKS 
 ForceChecks:

src/gravity_properties.c

@@ -23,6 +23,7 @@
 /* Standard headers */
 #include <float.h>
 #include <math.h>
+#include <string.h>
 
 /* Local headers. */
 #include "adiabatic_index.h"
@@ -84,10 +85,32 @@ void gravity_props_init(struct gravity_props *p, struct swift_params *params,
   /* Time integration */
   p->eta = parser_get_param_float(params, "Gravity:eta");
 
-  /* Opening angle */
+  /* Read the choice of multipole acceptance criterion */
+  char buffer[32] = {0};
+  parser_get_param_string(params, "Gravity:mulitpole_acceptance_criterion",
+                          buffer);
+
+  if (strcmp(buffer, "adaptive") == 0) {
+    p->use_adaptive_tolerance = 1;
+  } else if (strcmp(buffer, "geometric") == 0) {
+    p->use_adaptive_tolerance = 0;
+  } else {
+    error(
+        "Invalid choice of multipole acceptance criterion: '%s'. Should be "
+        "'adaptive' or 'geometric'",
+        buffer);
+  }
+
+  /* We always start with the geometric MAC */
+  p->use_advanced_mac = 0;
+
+  /* Geometric opening angle */
   p->theta_crit = parser_get_param_double(params, "Gravity:theta");
   if (p->theta_crit >= 1.) error("Theta too large. FMM won't converge.");
 
+  /* Adaptive opening angle tolerance */
+  p->adaptive_tolerance = parser_get_param_float(params, "Gravity:epsilon_fmm");
+
   /* Mesh dithering */
   if (periodic && !with_external_potential) {
     p->with_dithering =
@@ -170,6 +193,9 @@ void gravity_props_init(struct gravity_props *p, struct swift_params *params,
 void gravity_props_update(struct gravity_props *p,
                           const struct cosmology *cosmo) {
 
+  /* Choice of MAC */
+  if (p->use_adaptive_tolerance) p->use_advanced_mac = 1;
+
   /* Current softening length for the high-res. DM particles. */
   double DM_softening, baryon_softening;
   if (p->epsilon_DM_comoving * cosmo->a > p->epsilon_DM_max_physical)

src/gravity_properties.h

@@ -54,6 +54,9 @@ struct gravity_props {
 
   /* -------------- Properties of the FFM gravity ---------------------- */
 
+  /*! What MAC are we currently using? */
+  int use_advanced_mac;
+
   /*! Are we using the adaptive opening angle? */
   int use_adaptive_tolerance;
 

src/multipole_accept.h

@@ -89,7 +89,7 @@ __attribute__((nonnull, pure)) INLINE static int gravity_M2L_accept(
   /* Get the sum of the multipole sizes */
   const float rho_sum = rho_A + rho_B;
 
-  if (props->use_adaptive_tolerance) {
+  if (props->use_advanced_mac) {
 
     /* Test the different conditions */
 
@@ -181,7 +181,7 @@ __attribute__((nonnull, pure)) INLINE static int gravity_M2P_accept(
   const float theta_crit = props->theta_crit;
   const float theta_crit2 = theta_crit * theta_crit;
 
-  if (props->use_adaptive_tolerance) {
+  if (props->use_advanced_mac) {
 
     /* Test the different conditions */