Function SetIpoptProblemScaling 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn SetIpoptProblemScaling(
    ipopt_problem: IpoptProblem,
    obj_scaling: Number,
    x_scaling: *const Number,
    g_scaling: *const Number,
) -> Bool

Port of IpStdCInterface.cpp:SetIpoptProblemScaling. Stores user-provided NLP scaling on the problem; the scaling is forwarded to the solver via TNLP::get_scaling_parameters when the option nlp_scaling_method=user-scaling is set. Passing NULL for x_scaling / g_scaling disables scaling on that axis.

Always returns TRUE (the upstream contract). A non-trivial x_scaling is applied as a change of variables, so the solution and bound multipliers IpoptSolve writes back are in the caller’s own units (gh#486). A factor that is not finite and positive is refused at solve time, where IpoptSolve returns Invalid_Option and the journalist explains why: store-time validation is not an option, because the C signature has no way to report it.

Safety

ipopt_problem must be a valid IpoptProblem. When non-NULL, x_scaling must point to n doubles and g_scaling to m doubles; both arrays are copied internally.