nalgebra 0.13.0

extern crate alga;
extern crate nalgebra as na;


use alga::linear::Transformation;
use na::{Id, Vector3, Point3, Isometry3};

/*
 * Applies `n` times the transformation `t` to the vector `v` and sum each
 * intermediate value.
 */
fn complicated_algorithm<T>(v: &Vector3<f32>, t: &T, n: usize) -> Vector3<f32>
  where T: Transformation<Point3<f32>> {

  let mut result = *v;

  // Do lots of operations involving t.
  for _ in 0 .. n {
    result = v + t.transform_vector(&result);
  }

  result
}


/*
 * The two following calls are equivalent in term of result.
 */
fn main() {
  let v = Vector3::new(1.0, 2.0, 3.0);

  // The specialization generated by the compiler will do vector additions only.
  let result1 = complicated_algorithm(&v, &Id::new(), 100000);

  // The specialization generated by the compiler will also include matrix multiplications.
  let iso     = Isometry3::identity();
  let result2 = complicated_algorithm(&v, &iso, 100000);

  // They both return the same result.
  assert!(result1 == Vector3::new(100001.0, 200002.0, 300003.0));
  assert!(result2 == Vector3::new(100001.0, 200002.0, 300003.0));
}