bool FiniteDifferenceColoringWithUpdate::differenceProbe(const Epetra_Vector& x, Epetra_CrsMatrix& jac,const Epetra_MapColoring& colors){
// Allocate space for perturbation, get column version of x for scaling
Epetra_Vector xp(x);
Epetra_Vector *xcol;
int N=jac.NumMyRows();
if(jac.ColMap().SameAs(x.Map()))
xcol=const_cast<Epetra_Vector*>(&x);
else{
xcol=new Epetra_Vector(jac.ColMap(),true);//zeros out by default
xcol->Import(x,*jac.Importer(),InsertAdd);
}
// Counters for probing diagnostics
double tmp,probing_error_lower_bound=0.0,jc_norm=0.0;
// Grab coloring info (being very careful to ignore color 0)
int Ncolors=colors.MaxNumColors()+1;
int num_c0_global,num_c0_local=colors.NumElementsWithColor(0);
colors.Comm().MaxAll(&num_c0_local,&num_c0_global,1);
if(num_c0_global>0) Ncolors--;
if(Ncolors==0) return false;
// Pointers for Matrix Info
int entries, *indices;
double *values;
// NTS: Fix me
if ( diffType == Centered ) exit(1);
double scaleFactor = 1.0;
if ( diffType == Backward )
scaleFactor = -1.0;
// Compute RHS at initial solution
computeF(x,fo,NOX::Epetra::Interface::Required::FD_Res);
/* Probing, vector by vector since computeF does not have a MultiVector interface */
// Assume that anything with Color 0 gets ignored.
for(int j=1;j<Ncolors;j++){
xp=x;
for(int i=0;i<N;i++){
if(colors[i]==j)
xp[i] += scaleFactor*(alpha*abs(x[i])+beta);
}
computeF(xp, fp, NOX::Epetra::Interface::Required::FD_Res);
// Do the subtraction to estimate the Jacobian (w/o including step length)
Jc.Update(1.0, fp, -1.0, fo, 0.0);
// Relative error in probing
if(use_probing_diags){
Jc.Norm2(&tmp);
jc_norm+=tmp*tmp;
}
for(int i=0;i<N;i++){
// Skip for uncolored row/columns, else update entries
if(colors[i]==0) continue;
jac.ExtractMyRowView(i,entries,values,indices);
for(int k=0;k<jac.NumMyEntries(i);k++){
if(colors[indices[k]]==j){
values[k]=Jc[i] / (scaleFactor*(alpha*abs((*xcol)[indices[k]])+beta));
// If probing diagnostics are on, zero out the entries as they are used
if(use_probing_diags) Jc[i]=0.0;
break;// Only one value per row...
}
}
}
if(use_probing_diags){
Jc.Norm2(&tmp);
probing_error_lower_bound+=tmp*tmp;
}
}
// If diagnostics are requested, output Frobenius norm lower bound
if(use_probing_diags && !x.Comm().MyPID()) printf("Probing Error Lower Bound (Frobenius) abs = %6.4e rel = %6.4e\n",sqrt(probing_error_lower_bound),sqrt(probing_error_lower_bound)/sqrt(jc_norm));
// Cleanup
if(!jac.ColMap().SameAs(x.Map()))
delete xcol;
return true;
}
