Removed some unused variables

src/Matrix.cpp

@@ -531,7 +531,7 @@ void Matrix<rows, columns>::QRDecomposition(Matrix<rows, columns> &Q,
   Q.Fill(0);
   R.Fill(0);
   Matrix<rows, 1> a_col, e, u, Q_column_k{};
-  Matrix<1, rows> a_T, e_T{};
+  Matrix<1, rows> e_T{};
 
   for (uint8_t column = 0; column < columns; column++) {
     this->GetColumn(column, a_col);