bug in calc_gradient_penalty?

[lezhang-thu]

https://github.com/caogang/wgan-gp/blob/ae47a185ed2e938c39cf3eb2f06b32dc1b6a2064/gan_language.py#L159

Right before this line, it should be added "gradients = gradients.view(BATCH_SIZE, -1)"?

[t-ae]

It's OK in gan_mnist.py because real_data and fake_data has shape [BATCH_SZIE, OUTPUT_DIM], and Discriminator reshapes input at first. https://github.com/caogang/wgan-gp/blob/ae47a185ed2e938c39cf3eb2f06b32dc1b6a2064/gan_mnist.py#L100

But, in gan_cifar10.py, Discriminator requires input tensor to have rank 4. It means gradients also has rank 4. https://github.com/caogang/wgan-gp/blob/ae47a185ed2e938c39cf3eb2f06b32dc1b6a2064/gan_cifar10.py#L89-L93 So computation of gradient_penalty is not correct.

In original(?) implementation Discriminator requires rank 2 tensor. https://github.com/igul222/improved_wgan_training/blob/master/gan_cifar.py#L71

In gan_language.py, original Discriminator takes rank 3 tensor. But norm is computed along two axes. https://github.com/igul222/improved_wgan_training/blob/master/gan_language.py#L107