rssn 0.2.9

A comprehensive scientific computing library for Rust, aiming for feature parity with NumPy and SymPy.
Documentation 
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use std::os::raw::c_char;

use crate::ffi_apis::common::from_json_string;
use crate::ffi_apis::common::to_json_string;
use crate::symbolic::core::Expr;
use crate::symbolic::optimize::find_constrained_extrema;
use crate::symbolic::optimize::find_extrema;
use crate::symbolic::optimize::hessian_matrix;

/// Finds extrema of a function (JSON)
#[unsafe(no_mangle)]
pub extern "C" fn rssn_json_find_extrema(
    expr_json: *const c_char,
    vars_json: *const c_char,
) -> *mut c_char {
    let expr: Option<Expr> = from_json_string(expr_json);

    let vars: Option<Vec<String>> = from_json_string(vars_json);

    match (expr, vars) {
        | (Some(e), Some(v)) => {
            let vars_refs: Vec<&str> = v.iter().map(std::string::String::as_str).collect();

            match find_extrema(&e, &vars_refs) {
                | Ok(points) => to_json_string(&points),
                | Err(_) => std::ptr::null_mut(),
            }
        },
        | _ => std::ptr::null_mut(),
    }
}

/// Computes Hessian matrix (JSON)
#[unsafe(no_mangle)]
pub extern "C" fn rssn_json_hessian_matrix(
    expr_json: *const c_char,
    vars_json: *const c_char,
) -> *mut c_char {
    let expr: Option<Expr> = from_json_string(expr_json);

    let vars: Option<Vec<String>> = from_json_string(vars_json);

    match (expr, vars) {
        | (Some(e), Some(v)) => {
            let vars_refs: Vec<&str> = v.iter().map(std::string::String::as_str).collect();

            let hessian = hessian_matrix(&e, &vars_refs);

            to_json_string(&hessian)
        },
        | _ => std::ptr::null_mut(),
    }
}

/// Finds constrained extrema (JSON)
#[unsafe(no_mangle)]
pub extern "C" fn rssn_json_find_constrained_extrema(
    expr_json: *const c_char,
    constraints_json: *const c_char,
    vars_json: *const c_char,
) -> *mut c_char {
    let expr: Option<Expr> = from_json_string(expr_json);

    let constraints: Option<Vec<Expr>> = from_json_string(constraints_json);

    let vars: Option<Vec<String>> = from_json_string(vars_json);

    match (expr, constraints, vars) {
        | (Some(e), Some(c), Some(v)) => {
            let vars_refs: Vec<&str> = v.iter().map(std::string::String::as_str).collect();

            match find_constrained_extrema(&e, &c, &vars_refs) {
                | Ok(solutions) => to_json_string(&solutions),
                | Err(_) => std::ptr::null_mut(),
            }
        },
        | _ => std::ptr::null_mut(),
    }
}