Struct SquareMatrix 

pub struct SquareMatrix { /* private fields */ }

Row-major n×n dense matrix of f64. Maps to Foam::scalarSquareMatrix.

LU decomposition uses Crout’s algorithm with scaled partial pivoting, matching Foam::LUDecompose(scalarSquareMatrix&, labelList&).

Implementations

impl SquareMatrix

pub fn new(n: usize) -> Self

Allocate an n×n matrix initialised to all zeros.

pub fn n(&self) -> usize

The matrix order n (number of rows = number of columns).

pub fn get(&self, i: usize, j: usize) -> f64

Element in row i, column j (both 0-based, must be < n).

Out of range reads NaN, and never panics

i >= n or j >= n is a caller bug either way. Returning NaN rather than panicking is what lets this type be lifted verbatim into petir, which targets bare metal – there a panic is not a stack trace and a non-zero exit, it is the end of the program. NaN propagates through every later operation and compares unequal to everything, so the bug still surfaces, just downstream rather than at the read.

pub fn set(&mut self, i: usize, j: usize, v: f64)

Set the element in row i, column j to v (0-based indices < n).

Out of range is ignored, and never panics

See get for why this does not panic. A write with i >= n or j >= n is discarded; the matrix is left unchanged.

pub fn add(&mut self, i: usize, j: usize, v: f64)

Add v to the element in row i, column j (0-based indices < n).

Out of range is ignored, and never panics

See get. An accumulation with i >= n or j >= n is discarded.

pub fn fill_zero(&mut self)

Reset every entry to zero, keeping the same order n.

pub fn lu_decompose(&mut self) -> Vec<usize>

In-place LU decomposition with scaled partial pivoting.

After the call, self holds the combined LU factors (lower strictly triangular, upper including diagonal). Returns the pivot-row indices.

pub fn lu_back_substitute(&self, pivot: &[usize], b: &mut Vec<f64>)

Solve LU·x = b in-place (b is overwritten with the solution).

pivot must hold n entries and b must hold n values. A shorter one used to panic; it now returns early with b partly updated, so that this type can be lifted into petir, which targets bare metal where a panic ends the program. See get.

Must be called after lu_decompose. Matches Foam::LUBacksubstitute(scalarSquareMatrix&, labelList&, List<scalar>&).

pub fn solve(&self, rhs: &[f64]) -> Result<Vec<f64>, MatrixError>

Convenience: decompose a copy and solve A·x = b.

Returns Err(MatrixError::Singular) if the matrix has an exactly-zero pivot column (the LU sentinel f64::EPSILON was written to the diagonal). Ill-conditioned but non-singular matrices are not detected; for those, check the residual ‖Ax − b‖ manually.

Trait Implementations

impl Clone for SquareMatrix

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SquareMatrix

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.