void SQPInternal::evaluate(int nfdir, int nadir){
casadi_assert(nfdir==0 && nadir==0);
checkInitialBounds();
// Get problem data
const vector<double>& x_init = input(NLP_X_INIT).data();
const vector<double>& lbx = input(NLP_LBX).data();
const vector<double>& ubx = input(NLP_UBX).data();
const vector<double>& lbg = input(NLP_LBG).data();
const vector<double>& ubg = input(NLP_UBG).data();
// Set the static parameter
if (parametric_) {
const vector<double>& p = input(NLP_P).data();
if (!F_.isNull()) F_.setInput(p,F_.getNumInputs()-1);
if (!G_.isNull()) G_.setInput(p,G_.getNumInputs()-1);
if (!H_.isNull()) H_.setInput(p,H_.getNumInputs()-1);
if (!J_.isNull()) J_.setInput(p,J_.getNumInputs()-1);
}
// Set linearization point to initial guess
copy(x_init.begin(),x_init.end(),x_.begin());
// Lagrange multipliers of the NLP
fill(mu_.begin(),mu_.end(),0);
fill(mu_x_.begin(),mu_x_.end(),0);
// Initial constraint Jacobian
eval_jac_g(x_,gk_,Jk_);
// Initial objective gradient
eval_grad_f(x_,fk_,gf_);
// Initialize or reset the Hessian or Hessian approximation
reg_ = 0;
if( hess_mode_ == HESS_BFGS){
reset_h();
} else {
eval_h(x_,mu_,1.0,Bk_);
}
// Evaluate the initial gradient of the Lagrangian
copy(gf_.begin(),gf_.end(),gLag_.begin());
if(m_>0) DMatrix::mul_no_alloc_tn(Jk_,mu_,gLag_);
// gLag += mu_x_;
transform(gLag_.begin(),gLag_.end(),mu_x_.begin(),gLag_.begin(),plus<double>());
// Number of SQP iterations
int iter = 0;
// Number of line-search iterations
int ls_iter = 0;
// Last linesearch successfull
bool ls_success = true;
// Reset
merit_mem_.clear();
sigma_ = 0.; // NOTE: Move this into the main optimization loop
// Default stepsize
double t = 0;
// MAIN OPTIMIZATION LOOP
while(true){
// Primal infeasability
double pr_inf = primalInfeasibility(x_, lbx, ubx, gk_, lbg, ubg);
// 1-norm of lagrange gradient
double gLag_norm1 = norm_1(gLag_);
// 1-norm of step
double dx_norm1 = norm_1(dx_);
// Print header occasionally
if(iter % 10 == 0) printIteration(cout);
// Printing information about the actual iterate
printIteration(cout,iter,fk_,pr_inf,gLag_norm1,dx_norm1,reg_,ls_iter,ls_success);
// Call callback function if present
if (!callback_.isNull()) {
callback_.input(NLP_COST).set(fk_);
callback_.input(NLP_X_OPT).set(x_);
callback_.input(NLP_LAMBDA_G).set(mu_);
callback_.input(NLP_LAMBDA_X).set(mu_x_);
callback_.input(NLP_G).set(gk_);
callback_.evaluate();
if (callback_.output(0).at(0)) {
cout << endl;
cout << "CasADi::SQPMethod: aborted by callback..." << endl;
break;
}
}
// Checking convergence criteria
if (pr_inf < tol_pr_ && gLag_norm1 < tol_du_){
cout << endl;
cout << "CasADi::SQPMethod: Convergence achieved after " << iter << " iterations." << endl;
break;
}
if (iter >= maxiter_){
cout << endl;
cout << "CasADi::SQPMethod: Maximum number of iterations reached." << endl;
break;
}
// Start a new iteration
iter++;
// Formulate the QP
transform(lbx.begin(),lbx.end(),x_.begin(),qp_LBX_.begin(),minus<double>());
transform(ubx.begin(),ubx.end(),x_.begin(),qp_UBX_.begin(),minus<double>());
transform(lbg.begin(),lbg.end(),gk_.begin(),qp_LBA_.begin(),minus<double>());
transform(ubg.begin(),ubg.end(),gk_.begin(),qp_UBA_.begin(),minus<double>());
// Solve the QP
solve_QP(Bk_,gf_,qp_LBX_,qp_UBX_,Jk_,qp_LBA_,qp_UBA_,dx_,qp_DUAL_X_,qp_DUAL_A_);
log("QP solved");
// Detecting indefiniteness
double gain = quad_form(dx_,Bk_);
if (gain < 0){
casadi_warning("Indefinite Hessian detected...");
}
// Calculate penalty parameter of merit function
sigma_ = std::max(sigma_,1.01*norm_inf(qp_DUAL_X_));
sigma_ = std::max(sigma_,1.01*norm_inf(qp_DUAL_A_));
// Calculate L1-merit function in the actual iterate
double l1_infeas = primalInfeasibility(x_, lbx, ubx, gk_, lbg, ubg);
// Right-hand side of Armijo condition
double F_sens = inner_prod(dx_, gf_);
double L1dir = F_sens - sigma_ * l1_infeas;
double L1merit = fk_ + sigma_ * l1_infeas;
// Storing the actual merit function value in a list
merit_mem_.push_back(L1merit);
if (merit_mem_.size() > merit_memsize_){
merit_mem_.pop_front();
}
// Stepsize
t = 1.0;
double fk_cand;
// Merit function value in candidate
double L1merit_cand = 0;
// Reset line-search counter, success marker
ls_iter = 0;
ls_success = true;
// Line-search
log("Starting line-search");
if(maxiter_ls_>0){ // maxiter_ls_== 0 disables line-search
// Line-search loop
while (true){
for(int i=0; i<n_; ++i) x_cand_[i] = x_[i] + t * dx_[i];
// Evaluating objective and constraints
eval_f(x_cand_,fk_cand);
eval_g(x_cand_,gk_cand_);
ls_iter++;
// Calculating merit-function in candidate
l1_infeas = primalInfeasibility(x_cand_, lbx, ubx, gk_cand_, lbg, ubg);
L1merit_cand = fk_cand + sigma_ * l1_infeas;
// Calculating maximal merit function value so far
double meritmax = *max_element(merit_mem_.begin(), merit_mem_.end());
if (L1merit_cand <= meritmax + t * c1_ * L1dir){
// Accepting candidate
log("Line-search completed, candidate accepted");
break;
}
// Line-search not successful, but we accept it.
if(ls_iter == maxiter_ls_){
ls_success = false;
log("Line-search completed, maximum number of iterations");
break;
}
// Backtracking
t = beta_ * t;
}
}
// Candidate accepted, update dual variables
for(int i=0; i<m_; ++i) mu_[i] = t * qp_DUAL_A_[i] + (1 - t) * mu_[i];
for(int i=0; i<n_; ++i) mu_x_[i] = t * qp_DUAL_X_[i] + (1 - t) * mu_x_[i];
if( hess_mode_ == HESS_BFGS){
// Evaluate the gradient of the Lagrangian with the old x but new mu (for BFGS)
copy(gf_.begin(),gf_.end(),gLag_old_.begin());
if(m_>0) DMatrix::mul_no_alloc_tn(Jk_,mu_,gLag_old_);
// gLag_old += mu_x_;
transform(gLag_old_.begin(),gLag_old_.end(),mu_x_.begin(),gLag_old_.begin(),plus<double>());
}
// Candidate accepted, update the primal variable
copy(x_.begin(),x_.end(),x_old_.begin());
copy(x_cand_.begin(),x_cand_.end(),x_.begin());
// Evaluate the constraint Jacobian
log("Evaluating jac_g");
eval_jac_g(x_,gk_,Jk_);
// Evaluate the gradient of the objective function
log("Evaluating grad_f");
eval_grad_f(x_,fk_,gf_);
// Evaluate the gradient of the Lagrangian with the new x and new mu
copy(gf_.begin(),gf_.end(),gLag_.begin());
if(m_>0) DMatrix::mul_no_alloc_tn(Jk_,mu_,gLag_);
// gLag += mu_x_;
transform(gLag_.begin(),gLag_.end(),mu_x_.begin(),gLag_.begin(),plus<double>());
// Updating Lagrange Hessian
if( hess_mode_ == HESS_BFGS){
log("Updating Hessian (BFGS)");
// BFGS with careful updates and restarts
if (iter % lbfgs_memory_ == 0){
// Reset Hessian approximation by dropping all off-diagonal entries
const vector<int>& rowind = Bk_.rowind(); // Access sparsity (row offset)
const vector<int>& col = Bk_.col(); // Access sparsity (column)
vector<double>& data = Bk_.data(); // Access nonzero elements
for(int i=0; i<rowind.size()-1; ++i){ // Loop over the rows of the Hessian
for(int el=rowind[i]; el<rowind[i+1]; ++el){ // Loop over the nonzero elements of the row
if(i!=col[el]) data[el] = 0; // Remove if off-diagonal entries
}
}
}
// Pass to BFGS update function
bfgs_.setInput(Bk_,BFGS_BK);
bfgs_.setInput(x_,BFGS_X);
bfgs_.setInput(x_old_,BFGS_X_OLD);
bfgs_.setInput(gLag_,BFGS_GLAG);
bfgs_.setInput(gLag_old_,BFGS_GLAG_OLD);
// Update the Hessian approximation
bfgs_.evaluate();
// Get the updated Hessian
bfgs_.getOutput(Bk_);
} else {
// Exact Hessian
log("Evaluating hessian");
eval_h(x_,mu_,1.0,Bk_);
}
}
// Save results to outputs
output(NLP_COST).set(fk_);
output(NLP_X_OPT).set(x_);
output(NLP_LAMBDA_G).set(mu_);
output(NLP_LAMBDA_X).set(mu_x_);
output(NLP_G).set(gk_);
// Save statistics
stats_["iter_count"] = iter;
}
void RealtimeAPCSCP::solve() {
//Initialisation (calculate the exact solution for inital point)
int t_act = 0;
std::cout << "Time: " + to_string(t_act) << std::endl;
startIt = std::chrono::system_clock::now();
startSolver = std::chrono::system_clock::now();
//Solve the first problem exactly
std::map<std::string, Matrix<double> > arg = make_map("lbx",
model->getVMIN(), "ubx", model->getVMAX(), "lbg", this->G_bound,
"ubg", this->G_bound, "x0", model->getVINIT());
NlpSolver nlpSolver = NlpSolver("solver", "ipopt", nlp, opts);
nlpSolver.setOption("warn_initial_bounds", true);
nlpSolver.setOption("eval_errors_fatal", true);
std::map<string, Matrix<double>> result_tact = nlpSolver(arg);
endSolver = std::chrono::system_clock::now();
// Store data
assumedData[t_act] = result_tact["x"];
//Setup new iteration
model->storeAndShiftValues(result_tact, t_act);
storeStatsIpopt(&nlpSolver);
//Define values
this->x_act = result_tact["x"];
this->y_act = result_tact["lam_g"];
evaluateOriginalF(t_act,x_act);
updateA_act(t_act);
updateH_act(t_act);
updateM_act();
m_act = mul(transpose(Dg_act - A_act), y_act);
firstIteration = false;
opts["warm_start_init_point"] = "yes";
endIt = std::chrono::system_clock::now();
printTimingData(t_act);
//Iteration
for (t_act = 1; t_act < model->getN_F(); t_act++) {
std::cout << "Time: " + to_string(t_act) << std::endl;
startIt = std::chrono::system_clock::now();
startMS = std::chrono::system_clock::now();
G_sub = mul(A_act, model->getV() - x_act) + model->doMultipleShooting(x_act);
endMS = std::chrono::system_clock::now();
f_sub = model->getf(t_act) + mul(transpose(m_act), model->getV()
- x_act) + 0.5 * quad_form(model->getV() - x_act, H_act);
this->nlp_sub = MXFunction("nlp", nlpIn("x", model->getV()), nlpOut(
"f", f_sub, "g", G_sub));
this->nlp = MXFunction("nlp", nlpIn("x", model->getV()), nlpOut("f",
model->getf(t_act), "g", G));
// Step2 solve convex subproblem
startSolver = std::chrono::system_clock::now();
result_tact = solveConvexSubproblem();
endSolver = std::chrono::system_clock::now();
// Step3 update matrices and retrieve new measurement (step 1)
x_act = result_tact["x"];
y_act = result_tact["lam_g"];
model->storeAndShiftValues(result_tact, t_act);
// update
this->x_act = result_tact["x"];
this->y_act = result_tact["lam_g"];
evaluateOriginalF(t_act, x_act);
updateA_act(t_act);
updateH_act(t_act);
updateM_act();
endIt = std::chrono::system_clock::now();
printTimingData(t_act);
}
}
