diff --git a/russell_sparse/src/coo_matrix.rs b/russell_sparse/src/coo_matrix.rs
index c91941b3..66fe32a3 100644
--- a/russell_sparse/src/coo_matrix.rs
+++ b/russell_sparse/src/coo_matrix.rs
@@ -182,12 +182,11 @@ impl CooMatrix {
         self.pos = 0;
     }
 
-    /// Converts the CooMatrix to a dense matrix and returns the matrix
-    ///
-    /// Note: this function calls [CooMatrix::to_matrix].
+    /// Converts this CooMatrix to a dense matrix
     ///
     /// ```
-    /// use russell_sparse::{CooMatrix, Layout, StrError};
+    /// use russell_sparse::prelude::*;
+    /// use russell_sparse::StrError;
     ///
     /// fn main() -> Result<(), StrError> {
     ///     // define (4 x 4) sparse matrix with 6+1 non-zero values
@@ -202,7 +201,7 @@ impl CooMatrix {
     ///     coo.put(2, 2, 5.0)?;
     ///     coo.put(3, 3, 6.0)?;
     ///
-    ///     // convert to matrix
+    ///     // convert to dense
     ///     let a = coo.as_matrix();
     ///     let correct = "┌         ┐\n\
     ///                    │ 1 2 0 0 │\n\
@@ -220,20 +219,18 @@ impl CooMatrix {
         a
     }
 
-    /// Converts the CooMatrix to a dense matrix, up to a limit
-    ///
-    /// Note: see the function [CooMatrix::as_matrix] that returns the Matrix.
+    /// Converts this CooMatrix to a dense matrix
     ///
     /// # Input
     ///
-    /// `a` -- (nrow_max, ncol_max) matrix to hold the triplet data.
-    ///  The output matrix may have fewer rows or fewer columns than the triplet data.
+    /// * `a` -- where to store the dense matrix; must be (nrow, ncol)
     ///
-    /// # Example
+    /// # Examples
     ///
     /// ```
-    /// use russell_lab::{Matrix};
-    /// use russell_sparse::{CooMatrix, Layout, StrError};
+    /// use russell_lab::Matrix;
+    /// use russell_sparse::prelude::*;
+    /// use russell_sparse::StrError;
     ///
     /// fn main() -> Result<(), StrError> {
     ///     // define (4 x 4) sparse matrix with 6+1 non-zero values
@@ -248,47 +245,31 @@ impl CooMatrix {
     ///     coo.put(2, 2, 5.0)?;
     ///     coo.put(3, 3, 6.0)?;
     ///
-    ///     // convert the first (3 x 3) values
-    ///     let mut a = Matrix::new(3, 3);
+    ///     // convert to dense
+    ///     let mut a = Matrix::new(4, 4);
     ///     coo.to_matrix(&mut a)?;
-    ///     let correct = "┌       ┐\n\
-    ///                    │ 1 2 0 │\n\
-    ///                    │ 3 4 0 │\n\
-    ///                    │ 0 0 5 │\n\
-    ///                    └       ┘";
-    ///     assert_eq!(format!("{}", a), correct);
-    ///
-    ///     // convert the first (4 x 4) values
-    ///     let mut b = Matrix::new(4, 4);
-    ///     coo.to_matrix(&mut b)?;
     ///     let correct = "┌         ┐\n\
     ///                    │ 1 2 0 0 │\n\
     ///                    │ 3 4 0 0 │\n\
     ///                    │ 0 0 5 0 │\n\
     ///                    │ 0 0 0 6 │\n\
     ///                    └         ┘";
-    ///     assert_eq!(format!("{}", b), correct);
+    ///     assert_eq!(format!("{}", a), correct);
     ///     Ok(())
     /// }
     /// ```
     pub fn to_matrix(&self, a: &mut Matrix) -> Result<(), StrError> {
         let (m, n) = a.dims();
-        if m > self.nrow || n > self.ncol {
+        if m != self.nrow || n != self.ncol {
             return Err("wrong matrix dimensions");
         }
-        if self.layout != Layout::Full && m != n {
-            return Err("the resulting matrix must be square when the layout is either lower of upper triangular");
-        }
-        let m_i32 = to_i32(m);
-        let n_i32 = to_i32(n);
         a.fill(0.0);
         for p in 0..self.pos {
-            if self.indices_i[p] < m_i32 && self.indices_j[p] < n_i32 {
-                let (i, j) = (self.indices_i[p] as usize, self.indices_j[p] as usize);
-                a.add(i, j, self.values_aij[p]);
-                if self.layout != Layout::Full && i != j {
-                    a.add(j, i, self.values_aij[p]);
-                }
+            let i = self.indices_i[p] as usize;
+            let j = self.indices_j[p] as usize;
+            a.add(i, j, self.values_aij[p]);
+            if self.layout != Layout::Full && i != j {
+                a.add(j, i, self.values_aij[p]);
             }
         }
         Ok(())
@@ -481,10 +462,6 @@ mod tests {
         assert_eq!(a.get(1, 0), 3.0);
         assert_eq!(a.get(1, 1), 4.0);
         assert_eq!(a.get(2, 2), 5.0);
-        let mut b = Matrix::new(2, 1);
-        coo.to_matrix(&mut b).unwrap();
-        assert_eq!(b.get(0, 0), 1.0);
-        assert_eq!(b.get(1, 0), 3.0);
         // using as_matrix
         let bb = coo.as_matrix();
         assert_eq!(bb.get(0, 0), 1.0);
@@ -538,11 +515,6 @@ mod tests {
                        │ 0 4 0 │\n\
                        └       ┘";
         assert_eq!(format!("{}", a), correct);
-        let mut b = Matrix::new(2, 1);
-        assert_eq!(
-            coo.to_matrix(&mut b).err(),
-            Some("the resulting matrix must be square when the layout is either lower of upper triangular")
-        );
     }
 
     #[test]
@@ -560,11 +532,6 @@ mod tests {
                        │ 0 4 0 │\n\
                        └       ┘";
         assert_eq!(format!("{}", a), correct);
-        let mut b = Matrix::new(2, 1);
-        assert_eq!(
-            coo.to_matrix(&mut b).err(),
-            Some("the resulting matrix must be square when the layout is either lower of upper triangular")
-        );
     }
 
     #[test]
diff --git a/russell_sparse/src/csr_matrix.rs b/russell_sparse/src/csr_matrix.rs
index 790ea58f..84f4c6b2 100644
--- a/russell_sparse/src/csr_matrix.rs
+++ b/russell_sparse/src/csr_matrix.rs
@@ -170,7 +170,6 @@ impl CsrMatrix {
     /// # Examples
     ///
     /// ```
-    /// use russell_lab::Matrix;
     /// use russell_sparse::prelude::*;
     /// use russell_sparse::StrError;
     ///