quarterbit 8.0.2

Advanced neural network optimizers: Axiom (73% memory savings) + Verity (bit-perfect cross-hardware reproducibility)

QuarterBit AXIOM

High-Performance Quantized Optimizer for PyTorch

Drop-in replacement for AdamW with significant memory savings.

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Installation

pip install quarterbit

Requirements:

• Python 3.8+
• PyTorch 1.8+
• NVIDIA GPU with CUDA

Supported GPUs:

• Consumer: GTX 1650+, RTX 20/30/40 series
• Data Center: T4, V100, A10, A100, L4, L40, H100, H200

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Quick Start

from quarterbit import Axiom

optimizer = Axiom(model.parameters())

for batch in dataloader:
    loss = model(batch)
    loss.backward()
    optimizer.step()
    optimizer.zero_grad()

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Optimizer Parameters

AXIOM comes with tuned defaults. Advanced users can adjust:

from quarterbit import Axiom

optimizer = Axiom(
    params,                    # Model parameters
    lr=5e-4,                   # Learning rate
    betas=(0.9, 0.999),        # Momentum coefficients
    eps=1e-8,                  # Numerical stability
    weight_decay=0.1,          # Decoupled weight decay
    total_steps=10000,         # Training steps (for scheduling)
    warmup_ratio=0.1,          # Warmup fraction
)

Per-Layer Learning Rates

optimizer = Axiom([
    {'params': model.backbone.parameters(), 'lr': 1e-4},
    {'params': model.head.parameters(), 'lr': 5e-4},
], weight_decay=0.1)

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Activation Checkpointing (Pro)

Custom compressed checkpointing with slot-based storage.

from quarterbit.torch.utils import ActivationCheckpoint

# Create checkpoint storage
actcp = ActivationCheckpoint(
    max_slots=24,              # Number of layers/checkpoints
    max_elements=2**20,        # Max elements per activation
)

# During forward pass - store activations
actcp.store(activation, slot=layer_idx)

# During backward pass - restore activations
restored = actcp.restore(slot=layer_idx)

# Check memory savings
info = actcp.memory_info()
print(f"Memory saved: {info['savings_pct']:.1f}%")

# Clear when done
actcp.clear()

Parameters:

Parameter	Description
max_slots	Number of checkpoint slots (typically num_layers)
max_elements	Maximum tensor size per slot

Methods:

Method	Description
store(tensor, slot)	Compress and store activation
restore(slot)	Decompress and return activation
clear(slot=None)	Clear one slot or all
memory_info()	Get memory usage statistics

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Gradient Compression (Pro)

Drift-free compression with error feedback for distributed training.

from quarterbit.torch.utils import GradientCompressor

# Create compressor for each parameter
compressor = GradientCompressor(num_elements=param.numel())

# Compress before all-reduce
compressed = compressor.compress(param.grad)

# ... communicate compressed gradients ...

# Decompress after communication
param.grad = compressor.decompress(compressed)

# Reset error feedback (optional, between epochs)
compressor.reset()

Parameters:

Parameter	Description
num_elements	Number of gradient elements

Methods:

Method	Description
compress(grads)	Compress with error feedback
decompress(compressed)	Decompress to FP32
reset()	Clear error feedback accumulator

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Multi-GPU Training

DataParallel

model = torch.nn.DataParallel(model)
optimizer = Axiom(model.parameters())

DistributedDataParallel

from torch.nn.parallel import DistributedDataParallel as DDP

model = DDP(model, device_ids=[local_rank])
optimizer = Axiom(model.parameters())

DeepSpeed

import deepspeed

model, optimizer, _, _ = deepspeed.initialize(
    model=model,
    optimizer=Axiom(model.parameters()),
    config=ds_config
)

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Checkpointing

# Save
torch.save({
    'model': model.state_dict(),
    'optimizer': optimizer.state_dict(),
    'step': step,
}, 'checkpoint.pt')

# Load
ckpt = torch.load('checkpoint.pt')
model.load_state_dict(ckpt['model'])
optimizer.load_state_dict(ckpt['optimizer'])

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Licensing

quarterbit activate <LICENSE_KEY>

Tier	GPU Hours	Features
Free	10/month	Optimizer only
Pro	1,000/month	+ Checkpointing, Compression
Enterprise	Unlimited	+ On-premise, Custom SLA

Get your key: quarterbit.dev/pricing

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Links

• Website
• Documentation
• Pricing
• Support

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