array_matrix/matrix/
trace.rs

1use std::ops::Add;
2use num_traits::Zero;
3
4use super::SquareMatrix;
5
6pub trait Trace: SquareMatrix
7{
8    type Output;
9
10    /// Returns the trace of a given matrix
11    /// 
12    /// tr(A)
13    /// 
14    /// # Examples
15    /// 
16    /// ```rust
17    /// let a = [
18    ///     [1.0, 2.0, 3.0],
19    ///     [4.0, 5.0, 6.0],
20    ///     [7.0, 8.0, 9.0]
21    /// ];
22    /// let t = a[0][0] + a[1][1] + a[2][2];
23    /// assert_eq!(a.trace(), t);
24    /// ```
25    fn trace(&self) -> Self::Output;
26}
27
28impl<F, const N: usize> Trace for [[F; N]; N]
29where
30    Self: SquareMatrix,
31    F: Add<F, Output = F> + Clone + Zero
32{
33    type Output = F;
34    fn trace(&self) -> Self::Output
35    {
36        (0..N).map(|i| self[i][i].clone()).reduce(|a, b| a + b).unwrap_or(F::zero())
37    }
38}
array_matrix/matrix/trace.rs

array_matrix/matrix/
trace.rs
