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SecantRootFinding.cpp Go to the documentation of this file. /* ****************************************************************** ** ** OpenSees - Open System for Earthquake Engineering Simulation ** ** Pacific Earthquake Engineering Research Center ** ** ** ** ** ** (C) Copyright 2001, The Regents of the University of California ** ** All Rights Reserved. ** ** ** ** Commercial use of this program without express permission of the ** ** University of California, Berkeley, is strictly prohibited. See ** ** file 'COPYRIGHT' in main directory for information on usage and ** ** redistribution, and for a DISCLAIMER OF ALL WARRANTIES. ** ** ** ** Developed by: ** ** Frank McKenna (fmckenna@ce.berkeley.edu) ** ** Gregory L. Fenves (fenves@ce.berkeley.edu) ** ** Filip C. Filippou (filippou@ce.berkeley.edu) ** ** ** ** Reliability module developed by: ** ** Terje Haukaas (haukaas@ce.berkeley.edu) ** ** Armen Der Kiureghian (adk@ce.berkeley.edu) ** ** ** ** ****************************************************************** */ // $Revision: 1.1 $ // $Date: 2003/03/04 00:39:31 $ // $Source: /usr/local/cvs/OpenSees/SRC/reliability/analysis/rootFinding/SecantRootFinding.cpp,v $ // // Written by Terje Haukaas (haukaas@ce.berkeley.edu) // #include <SecantRootFinding.h> #include <RootFinding.h> #include <GFunEvaluator.h> #include <ProbabilityTransformation.h> #include <ReliabilityDomain.h> #include <RandomVariable.h> #include <math.h> #include <Vector.h> SecantRootFinding::SecantRootFinding( ReliabilityDomain *passedReliabilityDomain, ProbabilityTransformation *passedProbabilityTransformation, GFunEvaluator *passedGFunEvaluator, int passedMaxIter, double ptol, double pmaxStepLength) :RootFinding() { theReliabilityDomain = passedReliabilityDomain; theProbabilityTransformation = passedProbabilityTransformation; theGFunEvaluator = passedGFunEvaluator; maxIter = passedMaxIter; tol = ptol; maxStepLength = pmaxStepLength; } SecantRootFinding::~SecantRootFinding() { } Vector SecantRootFinding::findLimitStateSurface(int space, double g, Vector pDirection, Vector thePoint) { // Set scale factor for 'g' for convergence check double scaleG; if (fabs(g)>1.0e-4) { scaleG = g;} else { scaleG = 1.0;} // Normalize the direction vector Vector Direction = pDirection/pDirection.Norm(); // Scale 'maxStepLength' by standard deviation // (only if the user has specified to "walk" in original space) double perturbation; double realMaxStepLength = maxStepLength; if (space == 1) { // Go through direction vector and see which element is biggest // compared to its standard deviation int nrv = theReliabilityDomain->getNumberOfRandomVariables(); RandomVariable *theRV; double stdv, theStdv; int theBiggest; double maxRatio = 0.0; for (int i=0; i<nrv; i++) { theRV = theReliabilityDomain->getRandomVariablePtr(i+1); stdv = theRV->getStdv(); if (Direction(i)/stdv > maxRatio) { maxRatio = Direction(i)/stdv; theStdv = stdv; theBiggest = i+1; } } // Now scale so that 'maxStepSize' is related to the real stdv perturbation = maxStepLength * theStdv; realMaxStepLength = perturbation; } else { perturbation = maxStepLength; } Vector theTempPoint; double g_old, g_new; bool didNotConverge=true; double result; double tangent; int i=0; while (i<=maxIter && didNotConverge) { // Increment counter right away... i++; if (i!=1) { // Transform the point into x-space if the user has given it in 2-space if (space==2) { result = theProbabilityTransformation->set_u(thePoint); if (result < 0) { opserr << "GFunVisualizationAnalysis::analyze() - " << endln << " could not set u in the xu-transformation." << endln; return -1; } result = theProbabilityTransformation->transform_u_to_x(); if (result < 0) { opserr << "GFunVisualizationAnalysis::analyze() - " << endln << " could not transform from u to x and compute Jacobian." << endln; return -1; } theTempPoint = theProbabilityTransformation->get_x(); } else { theTempPoint = thePoint; } // Evaluate limit-state function result = theGFunEvaluator->runGFunAnalysis(theTempPoint); if (result < 0) { opserr << "GFunVisualizationAnalysis::analyze() - " << endln << " could not run analysis to evaluate limit-state function. " << endln; return -1; } result = theGFunEvaluator->evaluateG(theTempPoint); if (result < 0) { opserr << "GFunVisualizationAnalysis::analyze() - " << endln << " could not tokenize limit-state function. " << endln; return -1; } g_new = theGFunEvaluator->getG(); } else { g_new = g; } // Check convergence if (fabs(g_new/scaleG) < tol) { didNotConverge = false; } else { if (i==maxIter) { opserr << "WARNING: Projection scheme failed to find surface..." << endln; } else if (i==1) { thePoint = thePoint - perturbation * Direction; g_old = g_new; } else { // Take a step tangent = (g_new-g_old)/perturbation; perturbation = -g_new/tangent; if (fabs(perturbation) > realMaxStepLength) { perturbation = perturbation/fabs(perturbation)*realMaxStepLength; } thePoint = thePoint - perturbation * Direction; g_old = g_new; } } } return thePoint; } Generated on Mon Oct 23 15:05:25 2006 for OpenSees by  1.5.0

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