Fixed clippy warnings

src/error.rs

@@ -2,7 +2,7 @@ use std::error;
 use std::ffi::NulError;
 use std::fmt;
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, Eq, PartialEq)]
 pub enum Error {
     Io,
     Parameter(String),

src/matrix.rs

@@ -37,6 +37,12 @@ impl Matrix {
     }
 }
 
+impl Default for Matrix {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::Matrix;

src/model.rs

@@ -77,7 +77,7 @@ impl Model {
             let end_index = factors as usize * (row_index as usize + 1);
             return Some(&self.p_factors()[start_index..end_index]);
         }
-        return None;
+        None
     }
 
     pub fn q(&self, column_index: i32) -> Option<&[f32]> {
@@ -87,7 +87,7 @@ impl Model {
             let end_index = factors as usize * (column_index as usize + 1);
             return Some(&self.q_factors()[start_index..end_index]);
         }
-        return None;
+        None
     }
 
     pub fn rmse(&self, data: &Matrix) -> f64 {