Changeset 4714

Timestamp:

Sep 10, 2007, 4:12:43 PM (18 years ago)

Author:

ole

Message:

A small but obvious optimisation

File:

• anuga_core/source/anuga/shallow_water/shallow_water_ext.c (modified) (6 diffs)

anuga_core/source/anuga/shallow_water/shallow_water_ext.c

@@ -484 +484 @@
   double dz, hmin, alpha, h_diff;
 
-  //Compute linear combination between w-limited stages and
-  //h-limited stages close to the bed elevation.
+  // Compute linear combination between w-limited stages and
+  // h-limited stages close to the bed elevation.
 
   for (k=0; k<N; k++) {
@@ -497 +497 @@
     k3 = 3*k;
 
-    //FIXME: Try with this one precomputed
+    
     dz = 0.0;
-    hmin = hv[k3];
-    for (i=0; i<3; i++) {
-      if (tight_slope_limiters == 0) { 
-        dz = max(dz, fabs(zv[k3+i]-zc[k]));
-      }
-      
-      hmin = min(hmin, hv[k3+i]);
+    if (tight_slope_limiters == 0) {     
+      // FIXME: Try with this one precomputed
+      for (i=0; i<3; i++) {
+        dz = max(dz, fabs(zv[k3+i]-zc[k]));
+      }
     }
 
-
-    //Create alpha in [0,1], where alpha==0 means using the h-limited
-    //stage and alpha==1 means using the w-limited stage as
-    //computed by the gradient limiter (both 1st or 2nd order)
+    // Calculate minimal depth across all three vertices
+    hmin = min(hv[k3], min(hv[k3+1], hv[k3+2]));
     
     
+
+    // Create alpha in [0,1], where alpha==0 means using the h-limited
+    // stage and alpha==1 means using the w-limited stage as
+    // computed by the gradient limiter (both 1st or 2nd order)
     if (tight_slope_limiters == 0) {     
-      //If hmin > dz/alpha_balance then alpha = 1 and the bed will have no 
-      //effect
-      //If hmin < 0 then alpha = 0 reverting to constant height above bed.
-      //The parameter alpha_balance==2 by default 
+      // If hmin > dz/alpha_balance then alpha = 1 and the bed will have no 
+      // effect
+      // If hmin < 0 then alpha = 0 reverting to constant height above bed.
+      // The parameter alpha_balance==2 by default 
 
       
@@ -524 +524 @@
         alpha = max( min( alpha_balance*hmin/dz, 1.0), 0.0 );      
       } else {
-        alpha = 1.0;  //Flat bed
+        alpha = 1.0;  // Flat bed
       }
       //printf("Using old style limiter\n");
@@ -530 +530 @@
     } else {
 
-      // 2007 Balanced Limiter
+      // Tight Slope Limiter (2007)
     
       // Make alpha as large as possible but still ensure that 
@@ -591 +591 @@
         wv[k3+i] = zv[k3+i] + (1-alpha)*hvbar[k3+i] + alpha*hv[k3+i];
 
-        //Update momentum as a linear combination of
-        //xmomc and ymomc (shallow) and momentum
-        //from extrapolator xmomv and ymomv (deep).
-        //FIXME (Ole): Is this really needed?
+        // Update momentum as a linear combination of
+        // xmomc and ymomc (shallow) and momentum
+        // from extrapolator xmomv and ymomv (deep).
+        // FIXME (Ole): Is this really needed?
         xmomv[k3+i] = (1-alpha)*xmomc[k] + alpha*xmomv[k3+i];
         ymomv[k3+i] = (1-alpha)*ymomc[k] + alpha*ymomv[k3+i];
@@ -618 +618 @@
   double u, v, reduced_speed;
 
-  //Protect against initesimal and negative heights
+  // Protect against initesimal and negative heights
   for (k=0; k<N; k++) {
     hc = wc[k] - zc[k];