Solved by vdw in post #4 
              
              
                It’s less about reshaping but converting your input tuple (tensor1, tensor2, tensor3) to a tensor. What you can do is, for example: 
input = torch.zeros(3, batch_size, encoder_size)
tensor[0], tensor[1], tensor[2] = tensor1, tensor2, tensor3

This assumes that tensor1.shape = (batch_size, encoder_si…