collect the right quantities at the right times.

Former-commit-id: 982f19233d8ae55e6ae0a454e564059ea96c1fba

src/runner.c

@@ -860,15 +860,9 @@ void runner_dokick ( struct runner *r , struct cell *c , int timer ) {
             v[2] = v_old[2] + hdt * a[2];
             u = u_old + hdt * u_dt;
             
-            /* Collect momentum */
-            mom[0] += m * v[0];
-            mom[1] += m * v[1];
-            mom[2] += m * v[2];
-
-	        /* Collect angular momentum */
-	        ang[0] += m * ( x[1]*v[2] - x[2]*v[1] );
-	        ang[1] += m * ( x[2]*v[0] - x[0]*v[2] );
-	        ang[2] += m * ( x[0]*v[1] - x[1]*v[0] );
+            /* Collect total energy. */
+            ekin += 0.5 * m * ( v[0]*v[0] + v[1]*v[1] + v[2]*v[2] );
+            epot += m * u;
 
             /* Step and store the velocity and internal energy. */
             xp->v_old[0] = ( v_old[0] += dt * a[0] );
@@ -885,6 +879,16 @@ void runner_dokick ( struct runner *r , struct cell *c , int timer ) {
                         (x[2] - x_old[2])*(x[2] - x_old[2]) );
             dx_max = fmaxf( dx_max , dx );
 
+            /* Collect momentum */
+            mom[0] += m * v[0];
+            mom[1] += m * v[1];
+            mom[2] += m * v[2];
+
+	        /* Collect angular momentum */
+	        ang[0] += m * ( x[1]*v[2] - x[2]*v[1] );
+	        ang[1] += m * ( x[2]*v[0] - x[0]*v[2] );
+	        ang[2] += m * ( x[0]*v[1] - x[1]*v[0] );
+
             /* Update positions and energies at the half-step. */
             p->v[0] = v[0] + dt * a[0];
             p->v[1] = v[1] + dt * a[1];
@@ -901,10 +905,6 @@ void runner_dokick ( struct runner *r , struct cell *c , int timer ) {
                 p->h = h * expf( w );
             h_max = fmaxf( h_max , h );
 
-            /* Collect total energy. */
-            ekin += 0.5 * m * ( v[0]*v[0] + v[1]*v[1] + v[2]*v[2] );
-            epot += m * u;
-
             /* Init fields for density calculation. */
             p->density.wcount = 0.0f;
             p->density.wcount_dh = 0.0f;