I read and understand all simple cases for einsum, such as ab,bc->ac or batched ones like abc,acd->abd.

But “abc,cde->abde” is giving me a hard time. So far I figure there will be a sum on dim “c”. What does this einsum mean in matrix multiplication?

If anyone can write a plain matrix multiplication (maybe transpose, seqeeze, …) will help me understand. Thanks.

I searched online and asked GPT. I expect someone can write a plain matrix multiplication code to replace the einsum shown. This will help me understand.