rssn 0.2.9

A comprehensive scientific computing library for Rust, aiming for feature parity with NumPy and SymPy.
Documentation 
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//! Handle-based FFI API for physics FEM functions.

use std::ptr;

use crate::physics::physics_fem;

/// Solves 1D Poisson using FEM and returns a flat array of doubles.
/// The caller is responsible for freeing the memory using `rssn_free_f64_array`.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_physics_fem_solve_poisson_1d(
    n_elements: usize,
    domain_length: f64,
    out_size: *mut usize,
) -> *mut f64 {
    match physics_fem::solve_poisson_1d(n_elements, domain_length, |_| 2.0) {
        | Ok(res) => {
            unsafe {
                *out_size = res.len();
            }

            let mut res = res.into_boxed_slice();

            let ptr = res.as_mut_ptr();

            std::mem::forget(res);

            ptr
        },
        | Err(_) => {
            unsafe {
                *out_size = 0;
            }

            ptr::null_mut()
        },
    }
}

/// Frees a float64 array allocated by the FEM FFI.
///
/// # Safety
///
/// This function is unsafe because it dereferences raw pointers as part of the FFI boundary.
/// The caller must ensure:
/// 1. All pointer arguments are valid and point to initialized memory.
/// 2. The memory layout of passed structures matches the expected C-ABI layout.
/// 3. Any pointers returned by this function are managed according to the API's ownership rules.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn rssn_free_f64_array(
    ptr: *mut f64,
    size: usize,
) {
    unsafe {
        if !ptr.is_null() {
            let _ = Box::from_raw(std::ptr::slice_from_raw_parts_mut(ptr, size));
        }
    }
}