diff --git a/coord/base.hpp b/coord/base.hpp
index c2ff6ced..736741ad 100644
--- a/coord/base.hpp
+++ b/coord/base.hpp
@@ -73,13 +73,20 @@ namespace util::coord {
         }
 
         constexpr base (const base<S,T,SelfT> &rhs) = default;
-        base& operator= (const base<S,T,SelfT> &rhs) = default;
+        base& operator= (const base<S,T,SelfT> &rhs)& = default;
+        base& operator= (const T t)&
+        {
+            for (auto v: *this)
+                v = t;
+            return *this;
+        }
 
         // element accessors
-        T& operator[] (size_t i) { return this->data[i]; }
-        constexpr const T& operator[] (size_t i) const { return this->data[i]; }
-        T& operator[] (int i) { return this->data[i]; }
-        constexpr const T& operator[] (int i) const { return this->data[i]; }
+        constexpr T& operator[] (size_t i)& noexcept { return this->data[i]; }
+        constexpr T& operator[] (int i)& noexcept { return this->data[i]; }
+
+        constexpr const T& operator[] (size_t i) const& noexcept { return this->data[i]; }
+        constexpr const T& operator[] (int i) const& noexcept { return this->data[i]; }
 
         auto cbegin (void) const { return std::cbegin (this->data); }
         auto cend   (void) const { return std::cend   (this->data); }
diff --git a/coord/ops.hpp b/coord/ops.hpp
index a3967d12..1ca9e3f8 100644
--- a/coord/ops.hpp
+++ b/coord/ops.hpp
@@ -609,19 +609,16 @@ namespace util {
 
     //-------------------------------------------------------------------------
     template <
-        std::size_t S,
-        typename T,
-        template <std::size_t,typename> class A,
-        template <std::size_t,typename> class B,
+        typename A,
+        typename B,
         typename = std::enable_if_t<
-            is_coord_v<A<S,T>> && is_coord_v<B<S,T>>, void
+            is_coord_v<A> && is_coord_v<B>, void
         >
     >
-    constexpr
-    T
-    dot (A<S,T> a, B<S,T> b)
+    constexpr auto
+    dot (A a, B b)
     {
-        return dot<S,T> (a.data, b.data);
+        return dot (a.data, b.data);
     }
 
 
diff --git a/matrix.cpp b/matrix.cpp
index de04b8ef..d95f51df 100644
--- a/matrix.cpp
+++ b/matrix.cpp
@@ -352,7 +352,7 @@ util::operator<< (std::ostream &os, const matrix<Rows,Cols,T> &m)
 
     for (std::size_t i = 0; i < Rows; ++i) {
         os << "{ ";
-        std::copy_n (m[i], Cols, util::infix_iterator<float> (os, ", "));
+        std::copy (std::cbegin (m[i]), std::cend (m[i]), util::infix_iterator<float> (os, ", "));
         os << ((i == Rows - 1) ? " }" : " }, ");
     }
 
diff --git a/matrix.hpp b/matrix.hpp
index fb5d702b..d8b65063 100644
--- a/matrix.hpp
+++ b/matrix.hpp
@@ -34,17 +34,25 @@ namespace util {
         static constexpr auto rows = Rows;
         static constexpr auto cols = Cols;
 
+        using row_t = util::vector<Cols,T>;
+
+
+        ///////////////////////////////////////////////////////////////////////
         constexpr matrix () noexcept = default;
 
+
+        //---------------------------------------------------------------------
         constexpr matrix (const T(&_data)[Rows][Cols]) noexcept:
             values {}
         {
+            static_assert (sizeof (*this) == sizeof (T) * Rows * Cols);
             for (std::size_t r = 0; r < Rows; ++r)
                 for (std::size_t c = 0; c < Cols; ++c)
                     values[r][c] = _data[r][c];
         }
 
 
+        //---------------------------------------------------------------------
         template <std::size_t S, typename SelfT>
         constexpr matrix (const util::coord::base<S,T,SelfT> (&_data)[Rows]) noexcept
         {
@@ -53,55 +61,54 @@ namespace util {
                     values[r][c] = _data[r][c];
         }
 
-        T values[Rows][Cols];
 
         ///////////////////////////////////////////////////////////////////////
         // index operators return a pointer into the data array so that
         // multidimensional array syntax can be used transparently on this
         // type.
-        constexpr auto& operator[] (std::size_t idx) { return values[idx]; }
-        constexpr const auto& operator[] (std::size_t idx) const { return values[idx]; }
+        constexpr row_t& operator[] (std::size_t idx)& { return values[idx]; }
+        constexpr const row_t& operator[] (std::size_t idx) const& { return values[idx]; }
 
         //---------------------------------------------------------------------
-        constexpr auto
+        constexpr row_t*
         data (void)& noexcept
         {
-            return begin ();
+            return &values[0];
         }
 
         //---------------------------------------------------------------------
-        constexpr auto
+        constexpr const row_t*
         data (void) const& noexcept
         {
-            return begin ();
+            return &values[0];
         }
 
         //---------------------------------------------------------------------
         constexpr auto
         begin (void) const& noexcept
         {
-            return &(*this)[0][0];
-        }
-
-        //---------------------------------------------------------------------
-        constexpr auto
-        end (void) const& noexcept
-        {
-            return &(*this)[Rows][0];
+            return data ();
         }
 
         //---------------------------------------------------------------------
         constexpr auto
         begin (void)& noexcept
         {
-            return &(*this)[0][0];
+            return data ();
         }
 
         //---------------------------------------------------------------------
-        constexpr auto
+        constexpr row_t*
         end (void)& noexcept
         {
-            return &(*this)[Rows][0];
+            return &values[Rows];
+        }
+
+        //---------------------------------------------------------------------
+        constexpr const row_t*
+        end (void) const& noexcept
+        {
+            return &values[Rows];
         }
 
         //---------------------------------------------------------------------
@@ -138,8 +145,8 @@ namespace util {
         {
             VectorT out;
 
-            for (std::size_t i = 0; i < Rows; ++i)
-                out[i] = dot (rhs, values[i]);
+            for (std::size_t r = 0; r < Rows; ++r)
+                out[r] = dot (rhs, values[r]);
 
             return out;
         }
@@ -169,9 +176,13 @@ namespace util {
         matrix zeroes (void) noexcept
         {
             matrix ret {};
-            std::fill (std::begin (ret), std::end (ret), T{0});
+            std::fill (std::begin (ret), std::end (ret), row_t{0});
             return ret;
         }
+
+
+    private:
+        row_t values[Rows];
     };
 
 
@@ -346,7 +357,8 @@ namespace util {
     abs (const matrix<Rows,Cols,T> &src)
     {
         matrix<Rows,Cols,T> dst;
-        std::transform (std::cbegin (src), std::cend (src), std::begin (dst), util::abs<T>);
+        for (size_t r = 0; r < Rows; ++r)
+            dst[r] = abs (src[r]);
         return dst;
     }
 
@@ -355,7 +367,10 @@ namespace util {
     constexpr T
     sum (const matrix<Rows,Cols,T> &src)
     {
-        return sum (std::cbegin (src), std::cend (src));
+        util::vector<Rows,T> accum {};
+        for (size_t r = 0; r < Rows; ++r)
+            accum[r] = sum (src[r]);
+        return sum (accum);
     }
 
 
diff --git a/test/affine.cpp b/test/affine.cpp
index a7208972..b68e2ef4 100644
--- a/test/affine.cpp
+++ b/test/affine.cpp
@@ -104,9 +104,6 @@ test_mq_euler (util::TAP::logger &tap)
             util::quaternionf::angle_axis (t.z, { 0, 0, 1 })
         ).as_matrix ();
 
-        if (abs (m - q)[0])
-            exit (0);
-
         auto diff = util::sum (abs (m - q));
         tap.expect_le (diff, 1e-6f, "matrix-quaternion xyz euler rotations, %s", t.msg);
     }
diff --git a/test/matrix.cpp b/test/matrix.cpp
index 40e8d94d..dc962a71 100644
--- a/test/matrix.cpp
+++ b/test/matrix.cpp
@@ -112,9 +112,9 @@ main (void)
         for (size_t r = 0; r < m.rows; ++r)
             for (size_t c = 0; c < m.cols; ++c)
                 if (r == c)
-                    success = success && util::almost_equal (m.values[r][c], 1.f);
+                    success = success && util::almost_equal (m[r][c], 1.f);
                 else
-                    success = success && util::almost_equal (m.values[r][c], 0.f);
+                    success = success && util::almost_equal (m[r][c], 0.f);
 
         tap.expect (success, "identity inversion");
     }