Evaluating model complexity in highs avoiding device related performance

[nunzioono]

Hi, i'm running multiple instances of a model with a parameter. I want to evaluate how does the model variates his complexity as i increase the above parameter. I tought to avoid performance related biases to evaluate the growing complexity as number of the iterations of the simplex within highs.
I wonder if does exist a way to get this info at the current version of highs or if is a valid suggestion for a feature.
Thanks for your work.

[jajhall]

Fundamentally, the simplex iteration count is available from the C++ data structure

https://ergo-code.github.io/HiGHS/dev/structures/classes/HighsInfo/#HighsInfo

The same information is available via other language interfaces. If not C++, what are you using?

[nunzioono]

Now i'm using the rust version of highs through the good_lp crate

[jajhall]

It would appear from

https://docs.rs/highs-sys/1.6.2/highs_sys/

that you can use

https://docs.rs/highs-sys/1.6.2/highs_sys/fn.Highs_getIntInfoValue.html

by passing the name "simplex_iteration_count"

[nunzioono]

Thanks

[nunzioono]

I'm sorry but looking around i couldn't find any example in rust. I wouldn't bother, but i wrote the code with the function to get the iteration number, but i get an access violation error (memory related) since probably the struct which i'm passing to the function is not the correct one.
Could you help me understand which struct sholud i pass?
This is the code:
` let n = 4;

let mut c = vec![(n+1)*(n+2)/2; n+1];

c[4] = 12;

let variables = vars(n);
let mut problem = vars(n)
.minimise(obj(n, &variables))
.using(default_solver);

for constraint in bounds(n, &c, &variables) {
    let _ = problem.add_constraint(constraint);
}

let now = std::time::Instant::now();
let solution = problem.solve().unwrap();
let solution_internal_ptr: *const c_void = &solution as *const _ as *const c_void;

let mut iterations: i32 = 0;
let iterations_ptr: *mut i32 = &mut iterations;

unsafe {
    let info = CString::new("simplex_iteration_count").unwrap();
    let status = Highs_getIntInfoValue(solution_internal_ptr, info.as_ptr(), iterations_ptr);

    println!("Status: {:?}", status);
    println!("Iterations: {:?}", iterations);
}

let obj_expression = obj(n, &variables);
if obj_value(solution, obj_expression) == ((n+1)*(n+2)/2) as f64 {
    println!("Solution is valid, solved in {:.2?}", now.elapsed());
         
}`.

The struct i'm currently passing "solution_internal_ptr" in rust is an instance of HighsSolution

[nunzioono]

[jajhall]

Sorry, we didn't write the Rust interface, and don't know the language, so I can't help you. I suggest you contact @lovasoa and/or post an issue on the Rust repo