void LpToQp::init() {
// Initialize the base classes
LpSolverInternal::init();
// Create a QpSolver instance
solver_ = QpSolver(getOption(solvername()),
qpStruct("h", Sparsity::sparse(n_, n_),
"a", input(LP_SOLVER_A).sparsity()));
if (hasSetOption(optionsname())) solver_.setOption(getOption(optionsname()));
solver_.init();
}
void StabilizedQpToQp::init() {
// Initialize the base classes
StabilizedQpSolverInternal::init();
// Form augmented QP
Sparsity H_sparsity_qp = diagcat(st_[QP_STRUCT_H], Sparsity::diag(nc_));
Sparsity A_sparsity_qp = horzcat(st_[QP_STRUCT_A], Sparsity::diag(nc_));
std::string qp_solver_name = getOption("qp_solver");
qp_solver_ = QpSolver(qp_solver_name,
qpStruct("h", H_sparsity_qp, "a", A_sparsity_qp));
// Pass options if provided
if (hasSetOption("qp_solver_options")) {
Dictionary qp_solver_options = getOption("qp_solver_options");
qp_solver_.setOption(qp_solver_options);
}
// Initialize the QP solver
qp_solver_.init();
}
void Sqpmethod::init() {
// Call the init method of the base class
NlpSolverInternal::init();
// Read options
max_iter_ = getOption("max_iter");
max_iter_ls_ = getOption("max_iter_ls");
c1_ = getOption("c1");
beta_ = getOption("beta");
merit_memsize_ = getOption("merit_memory");
lbfgs_memory_ = getOption("lbfgs_memory");
tol_pr_ = getOption("tol_pr");
tol_du_ = getOption("tol_du");
regularize_ = getOption("regularize");
exact_hessian_ = getOption("hessian_approximation")=="exact";
min_step_size_ = getOption("min_step_size");
// Get/generate required functions
gradF();
jacG();
if (exact_hessian_) {
hessLag();
}
// Allocate a QP solver
Sparsity H_sparsity = exact_hessian_ ? hessLag().output().sparsity()
: Sparsity::dense(nx_, nx_);
H_sparsity = H_sparsity + Sparsity::diag(nx_);
Sparsity A_sparsity = jacG().isNull() ? Sparsity(0, nx_)
: jacG().output().sparsity();
// QP solver options
Dict qp_solver_options;
if (hasSetOption("qp_solver_options")) {
qp_solver_options = getOption("qp_solver_options");
}
// Allocate a QP solver
qp_solver_ = QpSolver("qp_solver", getOption("qp_solver"),
make_map("h", H_sparsity, "a", A_sparsity),
qp_solver_options);
// Lagrange multipliers of the NLP
mu_.resize(ng_);
mu_x_.resize(nx_);
// Lagrange gradient in the next iterate
gLag_.resize(nx_);
gLag_old_.resize(nx_);
// Current linearization point
x_.resize(nx_);
x_cand_.resize(nx_);
x_old_.resize(nx_);
// Constraint function value
gk_.resize(ng_);
gk_cand_.resize(ng_);
// Hessian approximation
Bk_ = DMatrix::zeros(H_sparsity);
// Jacobian
Jk_ = DMatrix::zeros(A_sparsity);
// Bounds of the QP
qp_LBA_.resize(ng_);
qp_UBA_.resize(ng_);
qp_LBX_.resize(nx_);
qp_UBX_.resize(nx_);
// QP solution
dx_.resize(nx_);
qp_DUAL_X_.resize(nx_);
qp_DUAL_A_.resize(ng_);
// Gradient of the objective
gf_.resize(nx_);
// Create Hessian update function
if (!exact_hessian_) {
// Create expressions corresponding to Bk, x, x_old, gLag and gLag_old
SX Bk = SX::sym("Bk", H_sparsity);
SX x = SX::sym("x", input(NLP_SOLVER_X0).sparsity());
SX x_old = SX::sym("x", x.sparsity());
SX gLag = SX::sym("gLag", x.sparsity());
SX gLag_old = SX::sym("gLag_old", x.sparsity());
SX sk = x - x_old;
SX yk = gLag - gLag_old;
SX qk = mul(Bk, sk);
// Calculating theta
SX skBksk = inner_prod(sk, qk);
SX omega = if_else(inner_prod(yk, sk) < 0.2 * inner_prod(sk, qk),
0.8 * skBksk / (skBksk - inner_prod(sk, yk)),
1);
yk = omega * yk + (1 - omega) * qk;
SX theta = 1. / inner_prod(sk, yk);
SX phi = 1. / inner_prod(qk, sk);
SX Bk_new = Bk + theta * mul(yk, yk.T()) - phi * mul(qk, qk.T());
// Inputs of the BFGS update function
vector<SX> bfgs_in(BFGS_NUM_IN);
bfgs_in[BFGS_BK] = Bk;
bfgs_in[BFGS_X] = x;
bfgs_in[BFGS_X_OLD] = x_old;
bfgs_in[BFGS_GLAG] = gLag;
bfgs_in[BFGS_GLAG_OLD] = gLag_old;
bfgs_ = SXFunction("bfgs", bfgs_in, make_vector(Bk_new));
// Initial Hessian approximation
B_init_ = DMatrix::eye(nx_);
}
// Header
if (static_cast<bool>(getOption("print_header"))) {
userOut()
<< "-------------------------------------------" << endl
<< "This is casadi::SQPMethod." << endl;
if (exact_hessian_) {
userOut() << "Using exact Hessian" << endl;
} else {
userOut() << "Using limited memory BFGS Hessian approximation" << endl;
}
userOut()
<< endl
<< "Number of variables: " << setw(9) << nx_ << endl
<< "Number of constraints: " << setw(9) << ng_ << endl
<< "Number of nonzeros in constraint Jacobian: " << setw(9) << A_sparsity.nnz() << endl
<< "Number of nonzeros in Lagrangian Hessian: " << setw(9) << H_sparsity.nnz() << endl
<< endl;
}
}
