Hi,
The problem is that your model is created in type float by default. So if you need it to be of a different type, you need to change it with: model.double(). after you created it.
Another thing, you cannot use .view() directly on the output of the lstm (because of the way the lstm returns its output), so you will get an error. You can use .reshape() here instead.
You will also get a size mismatch. between the output of the lstm and your linear. But most likely because you use the output of the 3 timesteps (192 features) and not only one (64 features).