addition: error implementation

src/lib.rs

@@ -1,6 +1,7 @@
 use fractions::{Fraction, FractionError};
 use std::cmp::min;
-use std::fmt::{Debug, Display};
+use std::error::Error;
+use std::fmt::{self, Debug, Display};
 use std::ops::Add;
 use std::ops::Mul;
 use std::ops::Sub;
@@ -27,6 +28,45 @@ impl From<FractionError> for MatrixError {
     }
 }
 
+impl fmt::Display for MatrixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            MatrixError::IndexOutOfRange => write!(f, "Index out of range"),
+            MatrixError::RowOutOfRange => write!(f, "Row index out of range"),
+            MatrixError::ColumnOutOfRange => write!(f, "Column index out of range"),
+            MatrixError::NotSquared => write!(f, "Matrix must be square"),
+            MatrixError::InvalidDataSize => write!(f, "Invalid data size for matrix"),
+            MatrixError::InvalidSizeForAdd => {
+                write!(f, "Matrices must have same dimensions for addition")
+            }
+            MatrixError::InvalidSizeForSub => {
+                write!(f, "Matrices must have same dimensions for subtraction")
+            }
+            MatrixError::InvalidSizeForMul => {
+                write!(f, "Invalid matrix dimensions for multiplication")
+            }
+            MatrixError::ZeroSize => write!(f, "Matrix cannot have zero rows or columns"),
+            MatrixError::FailedGauss => {
+                write!(f, "Gaussian elimination failed (possibly singular matrix)")
+            }
+            MatrixError::FailedGaussJordan => write!(
+                f,
+                "Gauss-Jordan elimination failed (possibly singular matrix)"
+            ),
+            MatrixError::FractionError(err) => write!(f, "Fraction error: {}", err),
+        }
+    }
+}
+
+impl Error for MatrixError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            MatrixError::FractionError(err) => Some(err),
+            _ => None,
+        }
+    }
+}
+
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct Matrix {
     rows: usize,