pub fn dense_solve(a: &[f64], b: &[f64], n: usize) -> SparseResult<Vec<f64>>Expand description
Solves the dense linear system A x = b via Gaussian elimination with
partial pivoting. a is row-major n × n; b has length n.
Used as the direct coarse-grid solver in algebraic multigrid.
§Errors
Returns SparseError::SingularMatrix if a pivot is numerically zero.