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Make random cov have correct diagonal; reset grad_min_rand to 0.

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This commit is contained in:
Daniel Povey 2022-06-18 17:04:44 +08:00
parent 3f0b57403e
commit 3fb3cc4e23
1 changed files with 11 additions and 5 deletions
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14
egs/librispeech/ASR/pruned_transducer_stateless7/optim.py
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@ -93,7 +93,7 @@ class NeutralGradient(Optimizer):
estimate_period=2000,
stats_steps=200,
param_pow=1.0,
grad_min_rand=0.2,
grad_min_rand=0.0,
lr_for_speedup=0.03,
speedup_recalibrate_period=100,
speedup_first_step=500,
@ -512,7 +512,8 @@ class NeutralGradient(Optimizer):
grad_cov = state[f"grad_cov_{dim}"] / count
del state[f"grad_cov_{dim}"] # save memory
self._randomize_lowrank_cov(grad_cov, count, p.shape)
self._randomize_lowrank_cov(grad_cov, count, p.shape,
grad_min_rand)
param_cov = self._get_param_cov(p, dim)
@ -703,22 +704,27 @@ class NeutralGradient(Optimizer):
size = cov.shape[0]
required_rank = int(size * 1.2) + 1
rand_scale = min_rand
if rank < required_rank:
# This epsilon is to avoid division by zero in weird situations where the
# params are exactly zero or we sample a zero matrix; the exact value is not
# going to affect the performance.
eps = 1.0e-20
cov_scale = cov.diag().mean() + 1.0e-20
# The following formula assumes that the "missing" outer products are
# expected to be smaller than the ones that we do have, i.e. 0.2 the size.
# We are trying to find the trace of the matrix we need to add,
# i.e. how big it is relative to the trace of the existing matrix.
missing_rank = (required_rank - rank)
rand_scale = max(min_rand, 0.2 * missing_rank / rank)
rand_scale = max(rand_scale, 0.2 * missing_rank / rank)
if rand_scale > 0.0:
R = torch.randn(size, size, device=cov.device, dtype=cov.dtype)
R = torch.matmul(R, R.t()) # positive semidefinite random matrix
rms_diag = (cov.diag() + 1.0e-20).sqrt()
R = R * rms_diag * rms_diag.unsqueeze(-1)
R_scale = R.diag().mean() + 1.0e-20
cov_scale = cov.diag().mean() + 1.0e-20
if random.random() < 0.1:
print(f"required_rank={required_rank}, rank={rank}, size={size}, R_scale={R_scale}, rand_scale={rand_scale}, shape={shape}")
cov.add_(R, alpha=rand_scale * cov_scale / R_scale)