Softened gravity in the interactions

src/gravity/Default/gravity.h

@@ -76,7 +76,9 @@ gravity_compute_timestep_self(const struct phys_const* const phys_const,
  * @param gp The particle to act upon
  */
 __attribute__((always_inline)) INLINE static void gravity_first_init_gpart(
-    struct gpart* gp) {}
+    struct gpart* gp) {
+  gp->epsilon = 0.1;  // MATTHIEU
+}
 
 /**
  * @brief Prepares a g-particle for the gravity calculation

src/gravity/Default/gravity_iact.h

@@ -47,31 +47,30 @@ __attribute__((always_inline)) INLINE static void runner_iact_grav_pp(
   const float uj = r * hj_inv;
   float fi, fj, W;
 
-  if(r >= hi) {
-    
+  if (r >= hi) {
+
     /* Get Newtonian graavity */
     fi = mj * ir * ir * ir;
-    
+
   } else {
-    
+
     /* Get softened gravity */
     kernel_grav_eval(ui, &W);
     fi = mj * hi_inv3 * W;
   }
 
-  if(r >= hj) {
-    
+  if (r >= hj) {
+
     /* Get Newtonian graavity */
     fj = mi * ir * ir * ir;
-    
+
   } else {
-    
+
     /* Get softened gravity */
     kernel_grav_eval(uj, &W);
     fj = mi * hj_inv3 * W;
   }
 
-  
   const float fidx[3] = {fi * dx[0], fi * dx[1], fi * dx[2]};
   gpi->a_grav[0] -= fidx[0];
   gpi->a_grav[1] -= fidx[1];