Fixed the aero functions such that they now cache their result when t…

…hey are executed. This is to make sure that their output to CSV is the same than the result that has been actually used for computations. The issue arose in particular for induced drag which is computed from aero/cl-squared which is modified between the moment where the induced drag is computed and the output to CSV is run. In some cases these 2 values can be very different.

src/models/FGAerodynamics.cpp

@@ -50,7 +50,7 @@ using namespace std;
 
 namespace JSBSim {
 
-IDENT(IdSrc,"$Id: FGAerodynamics.cpp,v 1.57 2015/01/31 14:56:21 bcoconni Exp $");
+IDENT(IdSrc,"$Id: FGAerodynamics.cpp,v 1.58 2016/05/22 17:02:13 bcoconni Exp $");
 IDENT(IdHdr,ID_AERODYNAMICS);
 
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -144,7 +144,7 @@ bool FGAerodynamics::Run(bool Holding)
   if (FGModel::Run(Holding)) return true;
   if (Holding) return false; // if paused don't execute
 
-  unsigned int axis_ctr, ctr;
+  unsigned int axis_ctr;
   const double twovel=2*in.Vt;
 
   RunPreFunctions();
@@ -179,15 +179,23 @@ bool FGAerodynamics::Run(bool Holding)
   vFnative.InitMatrix();
   vFnativeAtCG.InitMatrix();
 
-  for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
-    for (ctr=0; ctr < AeroFunctions[axis_ctr].size(); ctr++) {
-      vFnative(axis_ctr+1) += AeroFunctions[axis_ctr][ctr]->GetValue();
+  for (axis_ctr = 0; axis_ctr < 3; ++axis_ctr) {
+    AeroFunctionArray::iterator f;
+
+    AeroFunctionArray* array = &AeroFunctions[axis_ctr];
+    for (f=array->begin(); f != array->end(); ++f) {
+      // Tell the Functions to cache values, so when the function values are
+      // being requested for output, the functions do not get calculated again
+      // in a context that might have changed, but instead use the values that
+      // have already been calculated for this frame.
+      (*f)->cacheValue(true);
+      vFnative(axis_ctr+1) += (*f)->GetValue();
     }
-  }
 
-  for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
-    for (ctr=0; ctr < AeroFunctionsAtCG[axis_ctr].size(); ctr++) {
-      vFnativeAtCG(axis_ctr+1) += AeroFunctionsAtCG[axis_ctr][ctr]->GetValue();
+    array = &AeroFunctionsAtCG[axis_ctr];
+    for (f=array->begin(); f != array->end(); ++f) {
+      (*f)->cacheValue(true); // Same as above
+      vFnativeAtCG(axis_ctr+1) += (*f)->GetValue();
     }
   }
 
@@ -264,8 +272,14 @@ bool FGAerodynamics::Run(bool Holding)
   vMomentsMRC.InitMatrix();
 
   for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
-    for (ctr = 0; ctr < AeroFunctions[axis_ctr+3].size(); ctr++) {
-      vMomentsMRC(axis_ctr+1) += AeroFunctions[axis_ctr+3][ctr]->GetValue();
+    AeroFunctionArray* array = &AeroFunctions[axis_ctr+3];
+    for (AeroFunctionArray::iterator f=array->begin(); f != array->end(); ++f) {
+      // Tell the Functions to cache values, so when the function values are
+      // being requested for output, the functions do not get calculated again
+      // in a context that might have changed, but instead use the values that
+      // have already been calculated for this frame.
+      (*f)->cacheValue(true);
+      vMomentsMRC(axis_ctr+1) += (*f)->GetValue();
     }
   }
   vMoments = vMomentsMRC + vDXYZcg*vForces; // M = r X F
@@ -283,7 +297,7 @@ bool FGAerodynamics::Run(bool Holding)
 
 bool FGAerodynamics::Load(Element *document)
 {
-  string parameter, axis, scratch;
+  string axis;
   string scratch_unit="";
   Element *temp_element, *axis_element, *function_element;
 
@@ -333,15 +347,15 @@ bool FGAerodynamics::Load(Element *document)
       if (!apply_at_cg) {
       try {
         ca.push_back( new FGFunction(PropertyManager, function_element) );
-      } catch (string const str) {
+      } catch (const string& str) {
         cerr << endl << fgred << "Error loading aerodynamic function in " 
              << current_func_name << ":" << str << " Aborting." << reset << endl;
         return false;
       }
       } else {
         try {
           ca_atCG.push_back( new FGFunction(PropertyManager, function_element) );
-        } catch (string const str) {
+        } catch (const string& str) {
           cerr << endl << fgred << "Error loading aerodynamic function in " 
                << current_func_name << ":" << str << " Aborting." << reset << endl;
           return false;