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ODESolvers::seulex: Handle possible overflow in the calculation of the dy norm

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This commit is contained in:
Henry Weller
2016-06-17 18:59:28 +01:00
parent 988b5680ac
commit 1ef6ed3b9f
1 changed files with 32 additions and 24 deletions
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56
src/ODE/ODESolvers/seulex/seulex.C
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@ -38,7 +38,7 @@ namespace Foam
seulex::stepFactor1_ = 0.6,
seulex::stepFactor2_ = 0.93,
seulex::stepFactor3_ = 0.1,
seulex::stepFactor4_ = 4.0,
seulex::stepFactor4_ = 4,
seulex::stepFactor5_ = 0.5,
seulex::kFactor1_ = 0.7,
seulex::kFactor2_ = 0.9;
@ -50,11 +50,11 @@ namespace Foam
Foam::seulex::seulex(const ODESystem& ode, const dictionary& dict)
:
ODESolver(ode, dict),
jacRedo_(min(1.0e-4, min(relTol_))),
jacRedo_(min(1e-4, min(relTol_))),
nSeq_(iMaxx_),
cpu_(iMaxx_),
coeff_(iMaxx_, iMaxx_),
theta_(2.0*jacRedo_),
theta_(2*jacRedo_),
table_(kMaxx_, n_),
dfdx_(n_),
dfdy_(n_),
@ -70,7 +70,7 @@ Foam::seulex::seulex(const ODESystem& ode, const dictionary& dict)
dydx_(n_)
{
// The CPU time factors for the major parts of the algorithm
const scalar cpuFunc = 1.0, cpuJac = 5.0, cpuLU = 1.0, cpuSolve = 1.0;
const scalar cpuFunc = 1, cpuJac = 5, cpuLU = 1, cpuSolve = 1;
nSeq_[0] = 2;
nSeq_[1] = 3;
@ -92,7 +92,7 @@ Foam::seulex::seulex(const ODESystem& ode, const dictionary& dict)
for (int l=0; l<k; l++)
{
scalar ratio = scalar(nSeq_[k])/nSeq_[l];
coeff_(k, l) = 1.0/(ratio - 1.0);
coeff_(k, l) = 1/(ratio - 1);
}
}
}
@ -120,7 +120,7 @@ bool Foam::seulex::seul
a_(i, j) = -dfdy_(i, j);
}
a_(i, i) += 1.0/dx;
a_(i, i) += 1/dx;
}
LUDecompose(a_, pivotIndices_);
@ -138,7 +138,7 @@ bool Foam::seulex::seul
if (nn == 1 && k<=1)
{
scalar dy1 = 0.0;
scalar dy1 = 0;
for (label i=0; i<n_; i++)
{
dy1 += sqr(dy_[i]/scale[i]);
@ -153,15 +153,23 @@ bool Foam::seulex::seul
LUBacksubstitute(a_, pivotIndices_, dy_);
scalar dy2 = 0.0;
const scalar denom = min(1, dy1 + SMALL);
scalar dy2 = 0;
for (label i=0; i<n_; i++)
{
// Test of dy_[i] to avoid overflow
if (mag(dy_[i]) > scale[i]*denom)
{
theta_ = 1;
return false;
}
dy2 += sqr(dy_[i]/scale[i]);
}
dy2 = sqrt(dy2);
theta_ = dy2/min(1.0, dy1 + SMALL);
theta_ = dy2/denom;
if (theta_ > 1.0)
if (theta_ > 1)
{
return false;
}
@ -217,7 +225,7 @@ void Foam::seulex::solve
if (step.first || step.prevReject)
{
theta_ = 2.0*jacRedo_;
theta_ = 2*jacRedo_;
}
if (step.first)
@ -284,36 +292,36 @@ void Foam::seulex::solve
if (k != 0)
{
extrapolate(k, table_, y);
scalar err = 0.0;
scalar err = 0;
forAll(scale_, i)
{
scale_[i] = absTol_[i] + relTol_[i]*mag(y0_[i]);
err += sqr((y[i] - table_(0, i))/scale_[i]);
}
err = sqrt(err/n_);
if (err > 1.0/SMALL || (k > 1 && err >= errOld))
if (err > 1/SMALL || (k > 1 && err >= errOld))
{
step.reject = true;
dxNew = mag(dx)*stepFactor5_;
break;
}
errOld = min(4*err, 1);
scalar expo = 1.0/(k + 1);
scalar expo = 1/(k + 1);
scalar facmin = pow(stepFactor3_, expo);
scalar fac;
if (err == 0.0)
if (err == 0)
{
fac = 1.0/facmin;
fac = 1/facmin;
}
else
{
fac = stepFactor2_/pow(err/stepFactor1_, expo);
fac = max(facmin/stepFactor4_, min(1.0/facmin, fac));
fac = max(facmin/stepFactor4_, min(1/facmin, fac));
}
dxOpt_[k] = mag(dx*fac);
temp_[k] = cpu_[k]/dxOpt_[k];
if ((step.first || step.last) && err <= 1.0)
if ((step.first || step.last) && err <= 1)
{
break;
}
@ -325,11 +333,11 @@ void Foam::seulex::solve
&& !step.first && !step.last
)
{
if (err <= 1.0)
if (err <= 1)
{
break;
}
else if (err > nSeq_[kTarg_]*nSeq_[kTarg_ + 1]*4.0)
else if (err > nSeq_[kTarg_]*nSeq_[kTarg_ + 1]*4)
{
step.reject = true;
kTarg_ = k;
@ -344,11 +352,11 @@ void Foam::seulex::solve
if (k == kTarg_)
{
if (err <= 1.0)
if (err <= 1)
{
break;
}
else if (err > nSeq_[k + 1]*2.0)
else if (err > nSeq_[k + 1]*2)
{
step.reject = true;
if (kTarg_>1 && temp_[k-1] < kFactor1_*temp_[k])
@ -362,7 +370,7 @@ void Foam::seulex::solve
if (k == kTarg_+1)
{
if (err > 1.0)
if (err > 1)
{
step.reject = true;
if
@ -384,7 +392,7 @@ void Foam::seulex::solve
step.prevReject = true;
if (!jacUpdated)
{
theta_ = 2.0*jacRedo_;
theta_ = 2*jacRedo_;
if (theta_ > jacRedo_ && !jacUpdated)
{