coord/ops: add simple cosine wrapper

coord/ops.hpp

@@ -1391,7 +1391,27 @@ namespace std {
             return v;
         }
     };
-}
+
+    template <
+        typename CoordT,
+        typename = std::enable_if_t<
+            ::util::is_coord_v<CoordT>, void
+        >
+    >
+    auto cos (CoordT val)
+    {
+        CoordT out;
+
+        std::transform (
+            std::begin (val),
+            std::end   (val),
+            std::begin (out),
+            [] (auto i) { return ::std::cos (i); }
+        );
+
+        return out;
+    }
+};
 
 
 #endif