YarnBetaSlow

YarnBetaSlow is the “slow” boundary of YaRN’s correction range — the dimension index above which interpolation is fully applied. Relevant only when RopeScalingType is Yarn.

Quick reference

Type	float?
Default	null (use model default)
Range	Typical 1
Category	YaRN position encoding
Field on	ContextParameters.YarnBetaSlow

What it does

Pairs with YarnBetaFast to define the transition window between extrapolation and interpolation inside YaRN:

• Below YarnBetaFast: pure extrapolation.
• Between YarnBetaFast and YarnBetaSlow: blend.
• Above YarnBetaSlow: pure interpolation.

Typical YaRN recipe values: YarnBetaFast = 32, YarnBetaSlow = 1.

When to change it

Scenario	Value
Default (recommended)	null
Research / YaRN tuning	Per paper recipe

Example

var preset = new Llama32Preset();
preset.ContextParameters.RopeScalingType = RopeScalingType.Yarn;
// preset.ContextParameters.YarnBetaSlow = null; // default

Interactions

• YarnBetaFast — lower boundary.
• RopeScalingType — must be Yarn.

What’s next

• YarnBetaFast — companion lower boundary.
• Context parameters hub — all context knobs.