butterflies: fixed fractional generations

src/modules/butterflies/butterflies_populations.c

@@ -39,13 +39,12 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         struct grid_data_butterflies *data = grid->grid_modules[module_id].module_data;
 
         if (data->eggs[row][col] == 0) return;
+
         if (data->eggs[row][col] < 0) {
                 log_message(LOG_ERROR, "Number of eggs < 0: row %d col %d: %f", row, col, data->eggs[row][col]);
                 exit(EXIT_FAILURE);
         }
 
-        //int orig_eggs = data->eggs[row][col];
-
         // the number of generations per cell is usually not an integer value
         // the non-integer part of the number of generations is used in the generation which is
         // one greater than the integer part of the number of generations
@@ -60,16 +59,22 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         // then all the cells with have at least 4 (> 3) generations are modelled
         // ...
         // at last all cells with have at least 1 generation are modelled
-
+        struct conf_data_butterflies *module_conf = CATS_MODULE_DATA;
         float this_generation_fraction = 1.0f;
-        int32_t local_max_generation = (int32_t) ceilf(data->generations[row][col]);
-
-        if (data->generation_current == local_max_generation) {
-                this_generation_fraction = (float) local_max_generation - data->generations[row][col];
-                assert(this_generation_fraction >= 0);
-                assert(this_generation_fraction <= 1.0);
+        float local_generation = data->generations[row][col];
+        int32_t local_max_generation = (int32_t) ceilf(local_generation);
+        float current_generation_float = (float) data->generation_current;
+
+        if (current_generation_float == local_generation
+        || data->generation_current == module_conf->generations_min) {
+                this_generation_fraction = 1.0f;
+        } else if (data->generation_current == local_max_generation) {
+                this_generation_fraction = (float) local_max_generation - local_generation;
         }
 
+        assert(this_generation_fraction > 0);
+        assert(this_generation_fraction <= 1.0);
+
         //cats_dt_population max_cc = (cats_dt_population) grid->param.carrying_capacity.max_rate;
         float eggs = this_generation_fraction * data->eggs[row][col];
 
@@ -86,7 +91,7 @@ void bf_cell_maturation(struct cats_grid *grid, struct cats_thread_info *ts, cat
         if (eggs == 0) return;
 
         // not capped, we can have more adults than CC
-        struct conf_data_butterflies *module_conf = CATS_MODULE_DATA;
+
         cats_dt_environment suit = get_suitability(grid, row, col);
         cats_dt_rates reproduction_rate = calculate_rate(&module_conf->reproduction_rate, NAN, &grid->param,
                                                          grid, row, col, NULL);