Merge pull request #263 from benkay86/master

Make trace() require square matrix independent of layout

Author: termoshtt

ndarray-linalg/src/trace.rs

@@ -4,7 +4,6 @@ use ndarray::*;
 use std::iter::Sum;
 
 use super::error::*;
-use super::layout::*;
 use super::types::*;
 
 pub trait Trace {
@@ -20,7 +19,13 @@ where
     type Output = A;
 
     fn trace(&self) -> Result<Self::Output> {
-        let (n, _) = self.square_layout()?.size();
+        let n = match self.is_square() {
+            true => Ok(self.nrows()),
+            false => Err(LinalgError::NotSquare {
+                rows: self.nrows() as i32,
+                cols: self.ncols() as i32,
+            }),
+        }?;
         Ok((0..n as usize).map(|i| self[(i, i)]).sum())
     }
 }