ndarray_linalg/
trace.rs

1//! Trace calculation
2
3use ndarray::*;
4use std::iter::Sum;
5
6use super::error::*;
7use super::types::*;
8
9pub trait Trace {
10    type Output;
11    fn trace(&self) -> Result<Self::Output>;
12}
13
14impl<A> Trace for ArrayRef<A, Ix2>
15where
16    A: Scalar + Sum,
17{
18    type Output = A;
19
20    fn trace(&self) -> Result<Self::Output> {
21        let n = match self.is_square() {
22            true => Ok(self.nrows()),
23            false => Err(LinalgError::NotSquare {
24                rows: self.nrows() as i32,
25                cols: self.ncols() as i32,
26            }),
27        }?;
28        Ok((0..n as usize).map(|i| self[(i, i)]).sum())
29    }
30}