Method update

SRC/analysis/integrator/ExplicitDifferenceStatic.cpp:386–436

Update the response quantities

// Update the response quantities
int ExplicitDifferenceStatic::update(const Vector &Udotdot)
{
    updateCount++;
    if (updateCount > 2)  {
        opserr << "WARNING ExplicitDifferenceStatic::update() - called more than once -";
        opserr << " ExplicitDifferenceStatic integration scheme requires a LINEAR solution algorithm\n";
        return -1;
    }

    AnalysisModel *theModel = this->getAnalysisModel();
    if (theModel == 0)  {
        opserr << "WARNING ExplicitDifferenceStatic::update() - no AnalysisModel set\n";
        return -2;
    }

    if (Ut == 0)  {
        opserr << "WARNING ExplicitDifferenceStatic::update() - domainChange() failed or not called\n";
        return -3;
    }

    if (Udotdot.Size() != Utdotdot->Size()) {
        opserr << "WARNING ExplicitDifferenceStatic::update() - Vectors of incompatible size ";
        opserr << " expecting " << Utdotdot->Size() << " obtained " << Udotdot.Size() << endln;
        return -4;
    }

    // Update acceleration: weighted average for stability
    // a_{t+dt} = (3*a_new + a_old) / 4
    double halfT = deltaT * 0.125;

    Utdotdot1->addVector(0.0, Udotdot, 3.0);
    Utdotdot1->addVector(1.0, *Utdotdot, 1.0);

    // Update velocity for output (v at t+dt from leap-frog v at t+0.5*dt)
    Utdot1->addVector(0.0, *Utdot, 1.0);
    Utdot1->addVector(1.0, *Utdotdot1, halfT);

    // Set response in model
    theModel->setResponse(*Ut, *Utdot1, Udotdot);

    if (theModel->updateDomain() < 0)  {
        opserr << "ExplicitDifferenceStatic::update() - failed to update the domain\n";
        return -5;
    }

    // Store acceleration for next step
    (*Utdotdot) = Udotdot;
    (*Utdotdot1) = Udotdot;

    return 0;
}

// Commit the state
int ExplicitDifferenceStatic::commit(void)