bitsandbytes/pr_2030/en/reference/optim/lars.md

# LARS

[LARS (Layer-wise Adaptive Rate Scaling)](https:/hf.co/papers/1708.03888) is an optimizer designed for training with large batch sizes to accelerate training. LARS uses a separate learning rate for each *layer* instead of each parameter. The learning rate is calculated from a *trust ratio* between the weight and gradient norm in a layer. This helps calibrate a stable update size.

## LARS[[api-class]][[bitsandbytes.optim.LARS]]

#### bitsandbytes.optim.LARS[[bitsandbytes.optim.LARS]]

```python
bitsandbytes.optim.LARS(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, optim_bits = 32, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L11)

#### __init__[[bitsandbytes.optim.LARS.__init__]]

```python
__init__(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, optim_bits = 32, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L12)

**Parameters:**

params (`torch.tensor`) : The input parameters to optimize.

lr (`float`) : The learning rate.

momentum (`float`, defaults to 0) : The momentum value speeds up the optimizer by taking bigger steps.

dampening (`float`, defaults to 0) : The dampening value reduces the momentum of the optimizer.

weight_decay (`float`, defaults to 1e-2) : The weight decay value for the optimizer.

nesterov (`bool`, defaults to `False`) : Whether to use Nesterov momentum.

optim_bits (`int`, defaults to 32) : The number of bits of the optimizer state.

args (`object`, defaults to `None`) : An object with additional arguments.

min_8bit_size (`int`, defaults to 4096) : The minimum number of elements of the parameter tensors for 8-bit optimization.

max_unorm (`float`, defaults to 0.02) : The maximum gradient norm.

Base LARS optimizer.

## LARS8bit[[bitsandbytes.optim.LARS8bit]]

#### bitsandbytes.optim.LARS8bit[[bitsandbytes.optim.LARS8bit]]

```python
bitsandbytes.optim.LARS8bit(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L66)

#### __init__[[bitsandbytes.optim.LARS8bit.__init__]]

```python
__init__(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L67)

**Parameters:**

params (`torch.tensor`) : The input parameters to optimize.

lr (`float`) : The learning rate.

momentum (`float`, defaults to 0) : The momentum value speeds up the optimizer by taking bigger steps.

dampening (`float`, defaults to 0) : The dampening value reduces the momentum of the optimizer.

weight_decay (`float`, defaults to 1e-2) : The weight decay value for the optimizer.

nesterov (`bool`, defaults to `False`) : Whether to use Nesterov momentum.

args (`object`, defaults to `None`) : An object with additional arguments.

min_8bit_size (`int`, defaults to 4096) : The minimum number of elements of the parameter tensors for 8-bit optimization.

max_unorm (`float`, defaults to 0.02) : The maximum gradient norm.

8-bit LARS optimizer.

## LARS32bit[[bitsandbytes.optim.LARS32bit]]

#### bitsandbytes.optim.LARS32bit[[bitsandbytes.optim.LARS32bit]]

```python
bitsandbytes.optim.LARS32bit(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L118)

#### __init__[[bitsandbytes.optim.LARS32bit.__init__]]

```python
__init__(params, lr, momentum = 0, dampening = 0, weight_decay = 0, nesterov = False, args = None, min_8bit_size = 4096, max_unorm = 0.02)
```

[Source](https://github.com/bitsandbytes-foundation/bitsandbytes/blob/vr_2030/bitsandbytes/optim/lars.py#L119)

**Parameters:**

params (`torch.tensor`) : The input parameters to optimize.

lr (`float`) : The learning rate.

momentum (`float`, defaults to 0) : The momentum value speeds up the optimizer by taking bigger steps.

dampening (`float`, defaults to 0) : The dampening value reduces the momentum of the optimizer.

weight_decay (`float`, defaults to 1e-2) : The weight decay value for the optimizer.

nesterov (`bool`, defaults to `False`) : Whether to use Nesterov momentum.

args (`object`, defaults to `None`) : An object with additional arguments.

min_8bit_size (`int`, defaults to 4096) : The minimum number of elements of the parameter tensors for 8-bit optimization.

max_unorm (`float`, defaults to 0.02) : The maximum gradient norm.

32-bit LARS optimizer.