Define kernel_norm to simply code readability

src/hydro/Default/hydro.h

@@ -103,8 +103,8 @@ __attribute__((always_inline)) INLINE static void hydro_end_density(
   /* Finish the calculation by inserting the missing h-factors */
   p->rho *= ih * ih2;
   p->rho_dh *= ih4;
-  p->density.wcount *= (4.0f / 3.0f * M_PI * kernel_gamma3);
-  p->density.wcount_dh *= ih * (4.0f / 3.0f * M_PI * kernel_gamma4);
+  p->density.wcount *= kernel_norm;
+  p->density.wcount_dh *= ih * kernel_gamma * kernel_norm;
 
   const float irho = 1.f / p->rho;
 

src/hydro/Gadget2/hydro.h

@@ -97,8 +97,8 @@ __attribute__((always_inline)) INLINE static void hydro_end_density(
   /* Finish the calculation by inserting the missing h-factors */
   p->rho *= ih * ih2;
   p->rho_dh *= ih4;
-  p->density.wcount *= (4.0f / 3.0f * M_PI * kernel_gamma3);
-  p->density.wcount_dh *= ih * (4.0f / 3.0f * M_PI * kernel_gamma4);
+  p->density.wcount *= kernel_norm;
+  p->density.wcount_dh *= ih * kernel_gamma * kernel_norm;
 
   const float irho = 1.f / p->rho;
 

src/hydro/Minimal/hydro.h

@@ -106,8 +106,8 @@ __attribute__((always_inline)) INLINE static void hydro_end_density(
   /* Finish the calculation by inserting the missing h-factors */
   p->rho *= ih * ih2;
   p->rho_dh *= ih4;
-  p->density.wcount *= (4.0f / 3.0f * M_PI * kernel_gamma3);
-  p->density.wcount_dh *= ih * (4.0f / 3.0f * M_PI * kernel_gamma4);
+  p->density.wcount *= kernel_norm;
+  p->density.wcount_dh *= ih * kernel_gamma * kernel_norm;
 
   const float irho = 1.f / p->rho;
 

src/kernel_hydro.h

@@ -154,6 +154,9 @@ static const float kernel_coeffs[(kernel_degree + 1) * (kernel_ivals + 1)]
 #define kernel_root \
   ((float)(kernel_coeffs[kernel_degree]) * kernel_constant * kernel_igamma3)
 
+/* Kernel normalisation constant (volume term) */
+#define kernel_norm ((float)(4.0 * M_PI * kernel_gamma3 / 3.0))
+
 /**
  * @brief Computes the kernel function and its derivative.
  *