Please I need assistant trying to replicate result I got this error "AttributeError: module 'torch' has no attribute 'potrf"

[bisandud]

530 result = self._slow_forward(*input, **kwargs)
531 else:
--> 532 result = self.forward(*input, **kwargs)
533 for hook in self._forward_hooks.values():
534 hook_result = hook(self, input, result)

~\Dropbox\Implement2020\Codes\DNNETSC\matic_pytorch.py in forward(self, sample, return_gp)
92 err = lcdata[:, 2]
93 # Gaussian process fit
---> 94 mu, R, reg_points = self.GP_fit_posterior(mjd, mag, err, P)
95 # Sampling layer
96 z = self.sample_from_posterior(mu, R)

~\Dropbox\Implement2020\Codes\DNNETSC\matic_pytorch.py in GP_fit_posterior(self, mjd, mag, err, P, end, jitter)
66 Ktx = self.stationary_kernel(mjd, reg_points, non_trainable_kparams)
67 Kxx = self.stationary_kernel(reg_points, reg_points, non_trainable_kparams)
---> 68 Ltt = torch.potrf(Ktt, upper=False) # Cholesky lower triangular
69 # posterior mean and covariance
70 tmp1 = torch.t(torch.trtrs(Ktx, Ltt, upper=False)[0])

AttributeError: module 'torch' has no attribute 'potrf