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 numerical FEA functions.

use crate::numerical::physics_fea;

// ============================================================================
// Material Functions
// ============================================================================

/// Creates steel material and returns shear modulus.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_material_steel_shear_modulus() -> f64 {
    physics_fea::Material::steel().shear_modulus()
}

/// Creates aluminum material and returns shear modulus.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_material_aluminum_shear_modulus() -> f64 {
    physics_fea::Material::aluminum().shear_modulus()
}

/// Creates copper material and returns shear modulus.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_material_copper_shear_modulus() -> f64 {
    physics_fea::Material::copper().shear_modulus()
}

/// Computes shear modulus from Young's modulus and Poisson's ratio.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_shear_modulus(
    youngs_modulus: f64,
    poissons_ratio: f64,
) -> f64 {
    youngs_modulus / (2.0 * (1.0 + poissons_ratio))
}

/// Computes bulk modulus from Young's modulus and Poisson's ratio.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_bulk_modulus(
    youngs_modulus: f64,
    poissons_ratio: f64,
) -> f64 {
    youngs_modulus / (3.0 * 2.0f64.mul_add(-poissons_ratio, 1.0))
}

// ============================================================================
// 1D Element Functions
// ============================================================================

/// Computes and returns the stiffness value for a 1D linear element.
/// k = E * A / L
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_linear_element_1d_stiffness(
    length: f64,
    youngs_modulus: f64,
    area: f64,
) -> f64 {
    youngs_modulus * area / length
}

// ============================================================================
// Stress Analysis Functions
// ============================================================================

/// Computes von Mises stress from plane stress components.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_von_mises_stress(
    sx: f64,
    sy: f64,
    txy: f64,
) -> f64 {
    physics_fea::TriangleElement2D::von_mises_stress(&[sx, sy, txy])
}

/// Computes maximum shear stress from principal stresses.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_max_shear_stress(
    sigma1: f64,
    sigma2: f64,
) -> f64 {
    physics_fea::max_shear_stress(sigma1, sigma2)
}

/// Computes principal stresses from stress components.
/// Returns sigma1 in `out_sigma1`, sigma2 in `out_sigma2`, angle in `out_angle`.
///
/// # Safety
/// Pointers must be valid.
///
/// # 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_num_fea_principal_stresses(
    sx: f64,
    sy: f64,
    txy: f64,
    out_sigma1: *mut f64,
    out_sigma2: *mut f64,
    out_angle: *mut f64,
) -> i32 {
    unsafe {
        if out_sigma1.is_null() || out_sigma2.is_null() || out_angle.is_null() {
            return -1;
        }

        let (s1, s2, angle) = physics_fea::principal_stresses(&[sx, sy, txy]);

        *out_sigma1 = s1;

        *out_sigma2 = s2;

        *out_angle = angle;

        0
    }
}

/// Computes safety factor based on von Mises criterion.
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_safety_factor_von_mises(
    sx: f64,
    sy: f64,
    txy: f64,
    yield_strength: f64,
) -> f64 {
    physics_fea::safety_factor_von_mises(&[sx, sy, txy], yield_strength)
}

// ============================================================================
// Thermal Element Functions
// ============================================================================

/// Computes the conductivity value for a 1D thermal element.
/// k = κ * A / L
#[unsafe(no_mangle)]
pub extern "C" fn rssn_num_fea_thermal_element_1d_conductivity(
    length: f64,
    conductivity: f64,
    area: f64,
) -> f64 {
    conductivity * area / length
}