Temporal Loss - code vs. paper

[OriLifschitz]

Hello, impressive work and masterfully written paper!

This is the code for the temporal loss:
`

temporal loss

temporal_loss = 0
Laplacian = torch.squeeze(C_x + C_y)
for i in range(1, time_frame - 1):
temporal_loss += torch.sum(mask_cur[i:i + 1, 0, :, :] * (
(height_map_cuda[i + 1, :, :] + height_map_cuda[i - 1, :, :] - 2 * height_map_cuda[i, :, :] - 0.5 * Laplacian[i, :, :]) ** 2)
)
`
While this is the equation taken from the paper:

I am a bit confused regarding where did the constant 'c' in eq. (13) ("c is the magnitude of the velocity") disappeared in the code please?
Or where in the paper can I read about this change between paper and code please?

Thanks a lot !