OpenSees » SRC » reliability » analysis » direction

HLRFSearchDirection.cpp

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00001 /* ****************************************************************** **
00002 **    OpenSees - Open System for Earthquake Engineering Simulation    **
00003 **          Pacific Earthquake Engineering Research Center            **
00004 **                                                                    **
00005 **                                                                    **
00006 ** (C) Copyright 2001, The Regents of the University of California    **
00007 ** All Rights Reserved.                                               **
00008 **                                                                    **
00009 ** Commercial use of this program without express permission of the   **
00010 ** University of California, Berkeley, is strictly prohibited.  See   **
00011 ** file 'COPYRIGHT'  in main directory for information on usage and   **
00012 ** redistribution,  and for a DISCLAIMER OF ALL WARRANTIES.           **
00013 **                                                                    **
00014 ** Developed by:                                                      **
00015 **   Frank McKenna (fmckenna@ce.berkeley.edu)                         **
00016 **   Gregory L. Fenves (fenves@ce.berkeley.edu)                       **
00017 **   Filip C. Filippou (filippou@ce.berkeley.edu)                     **
00018 **                                                                    **
00019 ** Reliability module developed by:                                   **
00020 **   Terje Haukaas (haukaas@ce.berkeley.edu)                          **
00021 **   Armen Der Kiureghian (adk@ce.berkeley.edu)                       **
00022 **                                                                    **
00023 ** ****************************************************************** */
00024                                                                         
00025 // $Revision: 1.5 $
00026 // $Date: 2003/03/04 00:39:04 $
00027 // $Source: /usr/local/cvs/OpenSees/SRC/reliability/analysis/direction/HLRFSearchDirection.cpp,v $
00028 
00029 
00030 //
00031 // Written by Terje Haukaas (haukaas@ce.berkeley.edu) during Spring 2000
00032 // Revised: haukaas 06/00 (core code)
00033 //                      haukaas 06/01 (made part of official OpenSees)
00034 //
00035 
00036 #include <HLRFSearchDirection.h>
00037 #include <SearchDirection.h>
00038 #include <Vector.h>
00039 
00040 
00041 HLRFSearchDirection::HLRFSearchDirection()
00042 :SearchDirection(), searchDirection(1)
00043 {
00044 }
00045 
00046 HLRFSearchDirection::~HLRFSearchDirection()
00047 {
00048 }
00049 
00050 
00051 
00052 
00053 Vector
00054 HLRFSearchDirection::getSearchDirection()
00055 {
00056         return searchDirection;
00057 }
00058 
00059 
00060 
00061 int
00062 HLRFSearchDirection::computeSearchDirection(
00063                                                         int stepNumber,
00064                                                         Vector u, 
00065                                                         double gFunctionValue, 
00066                                                         Vector gradientInStandardNormalSpace )
00067 {
00068 
00069         // Compute the norm of the gradient
00070         double normOfGradient = gradientInStandardNormalSpace.Norm();
00071 
00072 
00073         // Check that the norm is not zero
00074         if (normOfGradient == 0.0) {
00075                 opserr << "HLRFSearchDirection::computeSearchDirection() - " << endln
00076                         << " the norm of the gradient is zero. " << endln;
00077                 return -1;
00078         }
00079 
00080         
00081         // Compute the alpha-vector
00082         Vector alpha = gradientInStandardNormalSpace * ( (-1) / normOfGradient );
00083 
00084 
00085         // Compute the direction vector
00086         double alpha_times_u = alpha ^ u ;
00087         Vector direction = alpha * ( gFunctionValue / normOfGradient + alpha_times_u ) - u;
00088 
00089         searchDirection = direction;
00090 
00091         return 0;
00092 }
00093

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