Also updated the Pressure-Entropy SPH scheme to use the new definition of the...

Also updated the Pressure-Entropy SPH scheme to use the new definition of the number of neighbours and its derivative. Back to correct results.

src/hydro/PressureEntropy/hydro.h

@@ -212,14 +212,15 @@ __attribute__((always_inline)) INLINE static void hydro_end_density(
   p->density.pressure_dh -=
       hydro_dimension * p->mass * p->entropy_one_over_gamma * kernel_root;
   p->density.wcount += kernel_root;
+  p->density.wcount_dh -= hydro_dimension * kernel_root;
 
   /* Finish the calculation by inserting the missing h-factors */
   p->rho *= h_inv_dim;
   p->rho_bar *= h_inv_dim;
   p->density.rho_dh *= h_inv_dim_plus_one;
   p->density.pressure_dh *= h_inv_dim_plus_one;
-  p->density.wcount *= kernel_norm;
-  p->density.wcount_dh *= h_inv * kernel_gamma * kernel_norm;
+  p->density.wcount *= h_inv_dim;
+  p->density.wcount_dh *= h_inv_dim_plus_one;
 
   const float rho_inv = 1.f / p->rho;
   const float entropy_minus_one_over_gamma = 1.f / p->entropy_one_over_gamma;

src/hydro/PressureEntropy/hydro_iact.h

@@ -59,7 +59,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_density(
 
   /* Compute contribution to the number of neighbours */
   pi->density.wcount += wi;
-  pi->density.wcount_dh -= ui * wi_dx;
+  pi->density.wcount_dh -= (hydro_dimension * wi + ui * wi_dx);
 
   /* Compute contribution to the weighted density */
   pi->rho_bar += mj * pj->entropy_one_over_gamma * wi;
@@ -77,7 +77,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_density(
 
   /* Compute contribution to the number of neighbours */
   pj->density.wcount += wj;
-  pj->density.wcount_dh -= uj * wj_dx;
+  pj->density.wcount_dh -= (hydro_dimension * wj + uj * wj_dx);
 
   /* Compute contribution to the weighted density */
   pj->rho_bar += mi * pi->entropy_one_over_gamma * wj;
@@ -147,7 +147,7 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_density(
 
   /* Compute contribution to the number of neighbours */
   pi->density.wcount += wi;
-  pi->density.wcount_dh -= ui * wi_dx;
+  pi->density.wcount_dh -= (hydro_dimension * wi + ui * wi_dx);
 
   /* Compute contribution to the weighted density */
   pi->rho_bar += mj * pj->entropy_one_over_gamma * wi;