Method newStep

SRC/analysis/integrator/ArcLength.cpp:129–223

}

int
ArcLength::newStep(void)
{
  // opserr<<"sewStep: start"<<endln;
//opserr<<"alpha2 is "<<alpha2<<endln;
    // get pointers to AnalysisModel and LinearSOE
    AnalysisModel *theModel = this->getAnalysisModel();
    LinearSOE *theLinSOE = this->getLinearSOE();    
    if (theModel == 0 || theLinSOE == 0) {
	opserr << "WARNING ArcLength::newStep() ";
	opserr << "No AnalysisModel or LinearSOE has been set\n";
	return -1;
    }

    // get the current load factor
    currentLambda = theModel->getCurrentDomainTime();

    if (deltaLambdaStep < 0)
	signLastDeltaLambdaStep = -1;
    else
	signLastDeltaLambdaStep = +1;

    // determine dUhat
    this->formTangent();
    theLinSOE->setB(*phat);
   // opserr<<" ArcLength: Phat is "<<*phat<<endln;
    if (theLinSOE->solve() < 0) {
      opserr << "ArcLength::newStep(void) - failed in solver\n";
      return -1;
    }

    (*deltaUhat) = theLinSOE->getX();
    Vector &dUhat = *deltaUhat;
    
    // determine delta lambda(1) == dlambda
    double dLambda = sqrt(arcLength2/((dUhat^dUhat)+alpha2));
    dLambda *= signLastDeltaLambdaStep; // base sign of load change
   //    opserr<<"newStep:   the sign is "<<signLastDeltaLambdaStep<<endln;     // on what was happening last step
    deltaLambdaStep = dLambda;
    dLAMBDA=dLambda;
  //  opserr<<"newStep:   dLAMBDA= "<<dLAMBDA<<endln;
    currentLambda += dLambda;

    // determine delta U(1) == dU
    (*deltaU) = dUhat;
    (*deltaU) *= dLambda;
    (*deltaUstep) = (*deltaU);
    (*deltaUstep2)=(*deltaU);

  // update model with delta lambda and delta U
    theModel->incrDisp(*deltaU);    
    //////

   if(this->activateSensitivity()==true) { 
          Domain *theDomain=theModel->getDomainPtr();
      ParameterIter &paramIter = theDomain->getParameters();
      Parameter *theParam;