RNG state is not saved

[evanberkowitz]

In principle it should be saved so that when we continue from an ensemble we have meaningfully one set of random numbers.

We can use torch.{get,set}_rng_state to get/set it. Probably this should be done somehow inside the MCMC. Should I save the state every trajectory / mcmc step? Is that overkill? The state seems to be 5056 uint8s = 40kb. That's 10x smaller than an 11^2*32 complex-double valued configuration.

So maybe storing it in an array and writing it out like an observable (one per configuration) is sensible?

[evanberkowitz]

Before deciding I should investigate the guarantees about hardware dependence etc. of the random seed. Is it always the same everywhere?

[evanberkowitz]

OF COURSE: the rng state is different on the CPU and GPU. So that's a headache! Makes chip independence quite annoying...

[evanberkowitz]

On the GPU

state = torch.cuda.get_rng_state(device)
print(state.shape)
print(state.dtype)

torch.Size([816]) torch.uint8

while on the CPU

cpu_state = torch.get_rng_state()
print(cpu_state.shape)
print(cpu_state.dtype)

torch.Size([5056]) torch.uint8