Construct Vector from Slice<1,M> alias row()

matrix/Vector.hpp

@@ -40,6 +40,15 @@ public:
     {
     }
 
+    template<size_t P, size_t Q, size_t DUMMY = 1>
+    Vector(const Slice<Type, 1, M, P, Q>& slice_in)
+    {
+        Vector &self(*this);
+        for (size_t i = 0; i<M; i++) {
+            self(i) = slice_in(0, i);
+        }
+    }
+
     inline const Type &operator()(size_t i) const
     {
         assert(i < M);

matrix/Vector2.hpp

@@ -48,6 +48,11 @@ public:
     {
     }
 
+    template<size_t P, size_t Q>
+    Vector2(const Slice<Type, 1, 2, P, Q>& slice_in) : Vector<Type, 2>(slice_in)
+    {
+    }
+
     explicit Vector2(const Vector3 & other)
     {
         Vector2 &v(*this);

matrix/Vector3.hpp

@@ -56,6 +56,11 @@ public:
     {
     }
 
+    template<size_t P, size_t Q>
+    Vector3(const Slice<Type, 1, 3, P, Q>& slice_in) : Vector<Type, 3>(slice_in)
+    {
+    }
+
     Vector3 cross(const Matrix31 & b) const {
         const Vector3 &a(*this);
         return {a(1)*b(2,0) - a(2)*b(1,0), -a(0)*b(2,0) + a(2)*b(0,0), a(0)*b(1,0) - a(1)*b(0,0)};