vector: move vector::is_zero to coord::almost_zero

coord/ops.hpp

@@ -312,6 +312,27 @@ namespace util {
     }
 
 
+    //-------------------------------------------------------------------------
+    template <
+        size_t S,
+        typename T,
+        template <size_t,typename> class K,
+        typename = std::enable_if_t<
+            is_coord_v<K>, void
+        >
+    >
+    constexpr
+    bool
+    almost_zero (const K<S,T> &k)
+    {
+        return std::all_of (
+            std::cbegin (k),
+            std::cend (k),
+            [] (T t) { return almost_equal (t); }
+        );
+    }
+
+
     ///////////////////////////////////////////////////////////////////////////
     // special operators
 

vector.cpp

@@ -154,18 +154,7 @@ util::cartesian_to_spherical (vector<3,T> c)
 }
 
 
-//-----------------------------------------------------------------------------
-template <size_t S, typename T>
-bool
-util::vector<S,T>::is_zero (void) const
-{
-    return std::all_of (std::begin (this->data),
-                        std::end   (this->data),
-                        [] (T i) { return almost_zero (i); });
-}
-
-
-//-----------------------------------------------------------------------------
+///////////////////////////////////////////////////////////////////////////////
 template <size_t S, typename T>
 const util::vector<S,T>
 util::vector<S,T>::UNIT (T{1});

vector.hpp

@@ -29,9 +29,6 @@ namespace util {
     {
         using coord::base<S,T,util::vector,coord::xyzw,coord::stpq>::base;
 
-        // vector size
-        bool is_zero (void) const;
-
         T difference  (vector<S,T>) const;
         T difference2 (vector<S,T>) const;