Function diagonal_f 

pub fn diagonal_f<R, T, B, D>(
    tensor: &TensorBase<Storage<R, T, B>, D>,
    diagonal_args: impl Into<DiagonalArgs>,
) -> Result<TensorBase<Storage<DataRef<'_, <B as DeviceRawAPI<T>>::Raw>, T, B>, <D as DimSmallerOneAPI>::SmallerOne>, Error>
where
    D: DimAPI + DimSmallerOneAPI,
    <D as DimSmallerOneAPI>::SmallerOne: DimAPI,
    R: DataAPI<Data = <B as DeviceRawAPI<T>>::Raw>,
    B: DeviceAPI<T>,