Broadcastable variables and arrays

I have read all the documentation about broadcast and searched on the web for “nd4j broadcast”.

I could not find any information to help me resolve this error:

shapes are not equal and are not broadcastable

The operation that fails is a simple sub

I tried using sub in samediff applying it do the two SD variables,
one with shape [32, 6, 33]
the other with shape [32, 6, 512]

I extracted the underlying arrays and tried the INDArray version of sub.

All with the same result.

I thought that even though the two variables/arrays do not have the same shape, under-the-cover broadcast would fix that and make sub work.

Clearly, I am doing something wrong and missing something obvious.

By the way, I also tried to use broadcast to try and align the two arrays. As expected, it did not work.

@adonnini broadcastable usually means you have something like an array minus a scalar or a matrix minus a vector.

You’ll have to put a 1 somewhere in there for it to work like reshape 1,3,1,2.