bool NOX::Direction::SteepestDescent::compute(Abstract::Vector& dir,
Abstract::Group& soln,
const Solver::Generic& solver)
{
NOX::Abstract::Group::ReturnType status;
// Compute F at current solution
status = soln.computeF();
if (status != NOX::Abstract::Group::Ok)
throwError("compute", "Unable to compute F");
// Compute Jacobian at current solution
status = soln.computeJacobian();
if (status != NOX::Abstract::Group::Ok)
throwError("compute", "Unable to compute Jacobian");
// Scale
switch (scaleType) {
case NOX::Direction::SteepestDescent::TwoNorm:
meritFuncPtr->computeGradient(soln, dir);
dir.scale(-1.0/dir.norm());
break;
case NOX::Direction::SteepestDescent::FunctionTwoNorm:
meritFuncPtr->computeGradient(soln, dir);
dir.scale(-1.0/soln.getNormF());
break;
case NOX::Direction::SteepestDescent::QuadMin:
meritFuncPtr->computeQuadraticMinimizer(soln, dir);
break;
case NOX::Direction::SteepestDescent::None:
meritFuncPtr->computeGradient(soln, dir);
dir.scale( -1.0 );
break;
default:
throwError("compute", "Invalid scaleType");
}
return true;
}
bool NonlinearCG::compute(Abstract::Vector& dir, Abstract::Group& soln,
const Solver::Generic& solver)
{
Abstract::Group::ReturnType ok;
// Initialize vector memory if haven't already
if(Teuchos::is_null(oldDirPtr))
oldDirPtr = soln.getX().clone(NOX::ShapeCopy);
if(Teuchos::is_null(oldDescentDirPtr))
oldDescentDirPtr = soln.getX().clone(NOX::ShapeCopy);
// These are conditionally created
if(Teuchos::is_null(diffVecPtr) && usePRbeta)
diffVecPtr = soln.getX().clone(NOX::ShapeCopy);
if(Teuchos::is_null(tmpVecPtr) && doPrecondition)
tmpVecPtr = soln.getX().clone(NOX::ShapeCopy);
// Get a reference to the old solution group (const)
oldSolnPtr = &solver.getPreviousSolutionGroup();
const Abstract::Group& oldSoln(*oldSolnPtr);
niter = solver.getNumIterations();
// Construct Residual and precondition (if desired) as first step in
// getting new search direction
ok = soln.computeF();
if (ok != Abstract::Group::Ok)
{
if (utils->isPrintType(Utils::Warning))
utils->out() << "NOX::Direction::NonlinearCG::compute - Unable to compute F." << std::endl;
return false;
}
dir = soln.getF();
if(doPrecondition)
{
if(!soln.isJacobian())
ok = soln.computeJacobian();
if (ok != Abstract::Group::Ok)
{
if (utils->isPrintType(Utils::Warning))
utils->out() << "NOX::Direction::NonlinearCG::compute - Unable to compute Jacobian." << std::endl;
return false;
}
*tmpVecPtr = dir;
ok = soln.applyRightPreconditioning(false, paramsPtr->sublist("Nonlinear CG").sublist("Linear Solver"), *tmpVecPtr, dir);
if( ok != Abstract::Group::Ok )
{
if (utils->isPrintType(Utils::Warning))
utils->out() << "NOX::Direction::NonlinearCG::compute - Unable to apply Right Preconditioner." << std::endl;
return false;
}
}
dir.scale(-1.0);
// Orthogonalize using previous search direction
beta = 0.0;
if( niter!=0 )
{
// Two choices (for now) for orthogonalizing descent direction with previous:
if( usePRbeta )
{
// Polak-Ribiere beta
*diffVecPtr = dir;
diffVecPtr->update(-1.0, *oldDescentDirPtr, 1.0);
double denominator = oldDescentDirPtr->innerProduct(oldSoln.getF());
beta = diffVecPtr->innerProduct(soln.getF()) / denominator;
// Constrain beta >= 0
if( beta < 0.0 )
{
if (utils->isPrintType(Utils::OuterIteration))
utils->out() << "BETA < 0, (" << beta << ") --> Resetting to zero" << std::endl;
beta = 0.0;
}
}
else
{
// Fletcher-Reeves beta
double denominator = oldDescentDirPtr->innerProduct(oldSoln.getF());
beta = dir.innerProduct(soln.getF()) / denominator;
}
// Allow for restart after specified number of nonlinear iterations
if( (niter % restartFrequency) == 0 )
{
if( utils->isPrintType(Utils::OuterIteration) )
utils->out() << "Resetting beta --> 0" << std::endl;
beta = 0 ; // Restart with Steepest Descent direction
}
} // niter != 0
*oldDescentDirPtr = dir;
dir.update(beta, *oldDirPtr, 1.0);
*oldDirPtr = dir;
return (ok == Abstract::Group::Ok);
}
