Read tree opening angle from YAML file.

examples/EAGLE_12/eagle_12.yml

@@ -28,7 +28,8 @@ Statistics:
 
 # Parameters for the self-gravity scheme
 Gravity:
-  eta:                   0.025    # Constant dimensionless multiplier for time integration. 
+  eta:                   0.025    # Constant dimensionless multiplier for time integration.
+  theta:                 0.7      # Opening angle (Multipole acceptance criterion)
   epsilon:               0.0001   # Softening length (in internal units).
   a_smooth:              1000.
   r_cut:                 4.

examples/parameter_example.yml

@@ -52,6 +52,7 @@ SPH:
 # Parameters for the self-gravity scheme
 Gravity:
   eta:                   0.025    # Constant dimensionless multiplier for time integration.
+  theta:                 0.7      # Opening angle (Multipole acceptance criterion)
   epsilon:               0.1      # Softening length (in internal units).
   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:                 4.5      # (Optional) Cut-off in number of top-level cells beyond which no FMM forces are computed (this is the default value).

src/gravity_properties.c

@@ -47,6 +47,10 @@ void gravity_props_init(struct gravity_props *p,
   /* Time integration */
   p->eta = parser_get_param_float(params, "Gravity:eta");
 
+  /* Opening angle */
+  p->theta = parser_get_param_double(params, "Gravity:theta");
+  p->theta_inv = 1. / p->theta;
+
   /* Softening lengths */
   p->epsilon = parser_get_param_double(params, "Gravity:epsilon");
   p->epsilon2 = p->epsilon * p->epsilon;
@@ -59,7 +63,9 @@ void gravity_props_print(const struct gravity_props *p) {
 
   message("Self-gravity time integration: eta=%.4f", p->eta);
 
-  message("Self-gravity softening: epsilon=%.4f", p->epsilon);
+  message("Self-gravity opening angle:  theta=%.4f", p->theta);
+
+  message("Self-gravity softening:    epsilon=%.4f", p->epsilon);
 
   if (p->a_smooth != gravity_props_default_a_smooth)
     message("Self-gravity smoothing-scale: a_smooth=%f", p->a_smooth);
@@ -73,7 +79,8 @@ void gravity_props_print_snapshot(hid_t h_grpgrav,
                                   const struct gravity_props *p) {
 
   io_write_attribute_f(h_grpgrav, "Time integration eta", p->eta);
-  io_write_attribute_f(h_grpgrav, "Softening", p->epsilon);
+  io_write_attribute_f(h_grpgrav, "Softening length", p->epsilon);
+  io_write_attribute_f(h_grpgrav, "Opening angle", p->theta);
   io_write_attribute_f(h_grpgrav, "MM a_smooth", p->a_smooth);
   io_write_attribute_f(h_grpgrav, "MM r_cut", p->r_cut);
 }

src/gravity_properties.h

@@ -41,6 +41,12 @@ struct gravity_props {
   /*! Time integration dimensionless multiplier */
   float eta;
 
+  /*! Tree opening angle (Multipole acceptance criterion) */
+  double theta;
+
+  /*! Inverse of opening angle */
+  double theta_inv;
+
   /*! Softening length */
   double epsilon;