howtospark
Training

Rotation / transform quant

QuantizationReference

Suppress outliers via rotations (QuaRot, SpinQuant, QuIP#, FlatQuant) to enable low-bit activations.

Relieves
CapacityBandwidthCompute
Targets
Weights · Activations
Format
INT4 / W4A4
Granularity
Per-group + Hadamard / learned rotation
Lifecycle
PTQ · no gradients
Calibration
Small calibration set
Compression
~4× (down to W4A4)
Quality
Recovers most FP16 at 4-bit incl. activations
Hardware
INT4/FP4 kernels + Hadamard transform support
Runtimes
vLLMTensorRT-LLM

A worked Spark recipe for this method hasn't been written yet — it lives here as a reference point in the ontology.