IpoptProgram

Ipopt solver interface implementing TNLP callbacks

Ipopt solver interface implementing TNLP callbacks

Adapts Gravity models to Ipopt's TNLP (Templated NLP) interface.

IpoptProgram Class:

• Inherits from Ipopt::TNLP and Program
• _model: Pointer to Gravity Model

Required TNLP Callbacks:

• get_nlp_info(): Return problem dimensions (n, m, nnz_jac, nnz_hess)
• get_bounds_info(): Variable and constraint bounds
• get_starting_point(): Initial x, z_L, z_U, lambda
• eval_f(): Objective function value
• eval_grad_f(): Objective gradient
• eval_g(): Constraint values
• eval_jac_g(): Jacobian values and structure
• eval_h(): Hessian of Lagrangian
• finalize_solution(): Copy solution back to model

Sparsity Pattern:

• First call to eval_jac_g/eval_h: return structure (iRow, jCol)
• Subsequent calls: return values only
• Gravity tracks via _first_call_jac, _first_call_hess

Solution Recovery:

• finalize_solution() copies x values to model variables
• Retrieves dual values (lambda) for constraints
• Retrieves bound multipliers (z_L, z_U)

Algorithm

See Also

• gravity/solver.h for unified solver interface
• layer-2/Ipopt/ for Ipopt implementation details

Source

Header file: `include/gravity/IpoptProgram.h`