Ejemplo n.º 1
0
NOX::Abstract::Group::ReturnType 
LOCA::StepSize::Adaptive::computeStepSize(
		     LOCA::MultiContinuation::AbstractStrategy& curGroup,
		     const LOCA::MultiContinuation::ExtendedVector& predictor,
		     const NOX::Solver::Generic& solver,
		     const LOCA::Abstract::Iterator::StepStatus& stepStatus,
		     const LOCA::Stepper& stepper,
		     double& stepSize) 
{
  // If this is the first step, set step size to initial value
  if (isFirstStep) {
    double dpds = predictor.getScalar(0);
    if (dpds != 0.0) {
      LOCA::StepSize::Constant::startStepSize /= dpds;
      LOCA::StepSize::Constant::maxStepSize /= dpds;
      LOCA::StepSize::Constant::minStepSize /= dpds;
    }
    LOCA::StepSize::Constant::isFirstStep = false;
    stepSize = LOCA::StepSize::Constant::startStepSize;
    prevStepSize = 0.0;
  }
  else {
  
    // A failed nonlinear solve cuts the step size in half
    if (stepStatus == LOCA::Abstract::Iterator::Unsuccessful) {
      stepSize *= LOCA::StepSize::Constant::failedFactor;    
    }
    else {

      double ds_ratio = curGroup.getStepSizeScaleFactor();
      LOCA::StepSize::Constant::startStepSize *= ds_ratio;
      LOCA::StepSize::Constant::maxStepSize *= ds_ratio;
      LOCA::StepSize::Constant::minStepSize *= ds_ratio;
      
      // Get number of nonlinear iterations in last step
      double numNonlinearSteps = 
	static_cast<double>(solver.getNumIterations());

      // Save successful stepsize as previous
      prevStepSize = stepSize;

      // adapive step size control
      double factor = (maxNonlinearSteps - numNonlinearSteps) 
               	      / (maxNonlinearSteps);

      stepSize *= (1.0 + agrValue * factor * factor);

      stepSize *= ds_ratio;
    } 
  }

  // Clip step size to be within prescribed bounds
  NOX::Abstract::Group::ReturnType res = clipStepSize(stepSize);

  return res;
}
Ejemplo n.º 2
0
NOX::Abstract::Group::ReturnType
LOCA::StepSize::Constant::computeStepSize(
             LOCA::MultiContinuation::AbstractStrategy& curGroup,
             const LOCA::MultiContinuation::ExtendedVector& predictor,
             const NOX::Solver::Generic& solver,
             const LOCA::Abstract::Iterator::StepStatus& stepStatus,
//             const LOCA::Stepper& stepper,
             const LOCA::Abstract::Iterator& stepper,
             double& stepSize)
{

  // If this is the first step, set step size to initial value adjusted
  // to predicted change in parameter
  if (isFirstStep) {
    double dpds = predictor.getScalar(0);
    if (dpds != 0.0) {
      startStepSize /= dpds;
      maxStepSize /= dpds;
      minStepSize /= dpds;
    }
    stepSize = startStepSize;
    isFirstStep = false;
    prevStepSize = 0.0;
  }
  else {

    // Step size remains constant, unless...
    // A failed nonlinear solve cuts the step size by failedFactor
    if (stepStatus == LOCA::Abstract::Iterator::Unsuccessful) {
      stepSize *= failedFactor;
    }
    else {

      double ds_ratio = curGroup.getStepSizeScaleFactor();
      startStepSize *= ds_ratio;
      maxStepSize *= ds_ratio;
      minStepSize *= ds_ratio;

      prevStepSize = stepSize;
      stepSize *= ds_ratio;

      // For constant step size, the step size may still have been
      // reduced by a solver failure.  We then increase the step size
      // by a factor of cube-root-2 until back to the original step size

      if (stepSize != startStepSize) {

        stepSize *= successFactor;

        if (startStepSize > 0.0)
          stepSize = NOX_MIN(stepSize, startStepSize);
        else
          stepSize = NOX_MAX(stepSize, startStepSize);
     }
    }
  }

  // Clip step size to be within prescribed bounds
  NOX::Abstract::Group::ReturnType res = clipStepSize(stepSize);

  return res;
}