@mohammad_gharaee , The shape of a in your code snippet would be [None, 128, 128] and shape of m_num would be [None, 4].
IMO, I don’t think they are multiplication compatible. I mean you can still multiply by broadcasting as @Bhack mentioned above but it doesn’t make sense to me in this case.
Can you mention a specific use case that you are trying to achieve here. May be then someone can help.