dimensioned::dim_unary!

macro_rules! dim_unary {
    ($Trait:ident, $op: ident, $($fun:ident),*) => (
        impl<D, V> $Trait for Dim<D, V>
            where D: $op<D>, V: $Trait, <D as $op<D>>::Output: Dimension {
                type Output = Dim<<D as $op<D>>::Output, <V as $Trait>::Output>;
                #[inline]
                $(fn $fun(self) -> Dim<<D as $op<D>>::Output, <V as $Trait>::Output> {
                    Dim( (self.0).$fun(), PhantomData )
                })*
            }
        )
}