OxiBLAS ndarray Integration

This crate provides seamless integration between OxiBLAS and the ndarray crate, allowing you to use OxiBLAS BLAS and LAPACK operations directly on ndarray types.

Features

• Conversions: Efficient conversion between ndarray and OxiBLAS matrix types
• BLAS Operations: Level 1-3 BLAS operations (dot, gemv, gemm, etc.)
• LAPACK Operations: Decompositions (LU, QR, SVD, EVD, Cholesky)
• Linear Solve: Direct and iterative solvers

Quick Start

use ndarray::{array, Array2};
use oxiblas_ndarray::prelude::*;

// Matrix multiplication
let a = Array2::from_shape_fn((2, 3), |(i, j)| (i * 3 + j + 1) as f64);
let b = Array2::from_shape_fn((3, 2), |(i, j)| (i * 2 + j + 1) as f64);
let c = matmul(&a, &b);
assert_eq!(c.dim(), (2, 2));

// Matrix-vector multiplication
let x = array![1.0f64, 2.0, 3.0];
let y = matvec(&a, &x);
assert_eq!(y.len(), 2);

// Dot product
let v1 = array![1.0f64, 2.0, 3.0];
let v2 = array![4.0f64, 5.0, 6.0];
let d = dot_ndarray(&v1, &v2);
assert!((d - 32.0).abs() < 1e-10);

LAPACK Operations

use ndarray::array;
use oxiblas_ndarray::prelude::*;

// Solve linear system
let a = array![[2.0f64, 1.0], [1.0, 3.0]];
let b = array![5.0f64, 7.0];
let x = solve_ndarray(&a, &b).unwrap();

// LU decomposition
let lu = lu_ndarray(&a).unwrap();
let det = lu.det();  // Determinant

// QR decomposition
let qr = qr_ndarray(&a).unwrap();

// SVD
let svd = svd_ndarray(&a).unwrap();

// Symmetric eigenvalue decomposition
let evd = eig_symmetric(&a).unwrap();

Memory Layout

OxiBLAS uses column-major (Fortran) order internally. This crate handles both row-major and column-major ndarray layouts:

• Column-major arrays: Zero-copy or minimal-copy operations
• Row-major arrays: Automatic conversion (with copy) when needed

For best performance, use column-major arrays when possible:

use ndarray::{Array2, ShapeBuilder};
use oxiblas_ndarray::prelude::*;

// Create column-major array (preferred)
let a: Array2<f64> = zeros_f(100, 100);
assert!(is_column_major(&a));

// Or convert existing row-major array
let row_major = Array2::<f64>::zeros((100, 100));
let col_major = to_column_major(&row_major);