nalgebra/examples/linear_system_resolution.rs

40 lines
1.1 KiB
Rust

#![cfg_attr(rustfmt, rustfmt_skip)]
#[macro_use]
extern crate approx; // for assert_relative_eq
extern crate nalgebra as na;
use na::{Matrix4, Matrix4x3, Vector4};
fn main() {
let a = Matrix4::new(
1.0, 1.0, 2.0, -5.0,
2.0, 5.0, -1.0, -9.0,
2.0, 1.0, -1.0, 3.0,
1.0, 3.0, 2.0, 7.0,
);
let mut b = Vector4::new(3.0, -3.0, -11.0, -5.0);
let decomp = a.lu();
let x = decomp.solve(&b).expect("Linear resolution failed.");
assert_relative_eq!(a * x, b);
/*
* It is possible to perform the resolution in-place.
* This is particularly useful to avoid allocations when
* `b` is a `DVector` or a `DMatrix`.
*/
assert!(decomp.solve_mut(&mut b), "Linear resolution failed.");
assert_relative_eq!(x, b);
/*
* It is possible to solve multiple systems
* simultaneously by using a matrix for `b`.
*/
let b = Matrix4x3::new(
3.0, 2.0, 0.0,
-3.0, 0.0, 0.0,
-11.0, 5.0, -3.0,
-5.0, 10.0, 4.0,
);
let x = decomp.solve(&b).expect("Linear resolution failed.");
assert_relative_eq!(a * x, b);
}