dimensioned::dim_impl_unary!

macro_rules! dim_impl_unary { ($Trait:ident, $fun:ident, $op:ident, $In:ty => $Out:ty) => (
    pub trait $Trait {
        type Output;
        fn $fun(self) -> Self::Output;
    }
    impl<D> $Trait for Dim<D, $In> where D: Dimension + $op, <D as $op>::Output: Dimension {
        type Output = Dim<<D as $op>::Output, $Out>;
        fn $fun(self) -> Self::Output { Dim::new( (self.0).$fun() ) }
    }
    );
}