ndarray_linalg/
norm.rs

1//! Norm of vectors
2
3use ndarray::*;
4use num_traits::Zero;
5
6use super::types::*;
7
8/// Define norm as a metric linear space (not as a matrix)
9///
10/// For operator norms, see opnorm module
11pub trait Norm {
12    type Output;
13    /// rename of `norm_l2`
14    fn norm(&self) -> Self::Output {
15        self.norm_l2()
16    }
17    /// L-1 norm
18    fn norm_l1(&self) -> Self::Output;
19    /// L-2 norm
20    fn norm_l2(&self) -> Self::Output;
21    /// maximum norm
22    fn norm_max(&self) -> Self::Output;
23}
24
25impl<A, S, D> Norm for ArrayBase<S, D>
26where
27    A: Scalar + Lapack,
28    S: Data<Elem = A>,
29    D: Dimension,
30{
31    type Output = A::Real;
32    fn norm_l1(&self) -> Self::Output {
33        self.iter().map(|x| x.abs()).sum()
34    }
35    fn norm_l2(&self) -> Self::Output {
36        self.iter().map(|x| x.square()).sum::<A::Real>().sqrt()
37    }
38    fn norm_max(&self) -> Self::Output {
39        self.iter().fold(A::Real::zero(), |f, &val| {
40            let v = val.abs();
41            if f > v {
42                f
43            } else {
44                v
45            }
46        })
47    }
48}
49
50pub enum NormalizeAxis {
51    Row = 0,
52    Column = 1,
53}
54
55/// normalize in L2 norm
56pub fn normalize<A, S>(
57    mut m: ArrayBase<S, Ix2>,
58    axis: NormalizeAxis,
59) -> (ArrayBase<S, Ix2>, Vec<A::Real>)
60where
61    A: Scalar + Lapack,
62    S: DataMut<Elem = A>,
63{
64    let mut ms = Vec::new();
65    for mut v in m.axis_iter_mut(Axis(axis as usize)) {
66        let n = v.norm();
67        ms.push(n);
68        v.map_inplace(|x| *x /= A::from_real(n))
69    }
70    (m, ms)
71}
ndarray_linalg/norm.rs

ndarray_linalg/
norm.rs
