Struct PiecewisePayout

pub struct PiecewisePayout;

The PiecewisePayout model computes rewards using a piecewise-defined function, selecting different behaviors depending on the input range.

Concept: Segmented Reward Function

Formula

reward(x) = f_i(x),  for the first segment i where x is in [start_x_i, end_x_i]
            0,        if no segment matches

Segment Types

• Linear: y = start_y + t * (end_y - start_y) where t = (x - x1) / (x2 - x1). Supports both increasing and decreasing slopes for signed and unsigned types.
• Curve: y = L / (1 + e^(-k*(x - x0))). Works correctly for unsigned types; signed arithmetic handled via FixedI128.

Signed Arithmetic

Two sub-computations require signed intermediates that unsigned fixed-point cannot represent:

• Curve segments: x - x0 is negative for x < x0 (the left sigmoid tail). The old code clamped this to 0 via unsigned saturating_sub, flattening the entire left half of every curve segment.
• Decreasing linear segments: end_y - start_y is negative when end_y < start_y. The old code clamped to 0, turning every ramp-down into a flat line.

Both are now computed in concrete FixedI128 via FixedSignedCast.

Characteristics:

• Composable: Combine Linear and Curve segments freely.
• Works with unsigned types: No Neg bound, signed arithmetic in FixedI128.
• Deterministic: Same input and configuration yield identical output.
• Context-driven: Controlled via PiecewiseConfig.

Applications:

• Multi-phase emission schedules.
• Bootstrap, growth, and stabilization curves.
• DeFi incentive design.
• Tiered reward systems.

Example

// Linear ramp: x in [0, 10] maps reward from 0 to 100.
let config = PiecewiseConfig {
    segments: vec![
        Segment::Linear {
            start_x: FixedU128::zero(),
            end_x:   FixedU128::saturating_from_integer(10),
            start_y: FixedU128::zero(),
            end_y:   FixedU128::saturating_from_integer(100),
        }
    ],
};
assert_eq!(PiecewisePayout::compute(5u128, Some(config)), 50);

Trait Implementations

impl Debug for PiecewisePayout

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PiecewisePayout

fn default() -> PiecewisePayout

Returns the “default value” for a type.

impl<FixedPoint, Asset> PurePluginModel<Asset, PiecewiseConfig<FixedPoint>, Asset> for PiecewisePayout

where Asset: Copy + IntegerToFixed + FixedForInteger<FixedPoint = FixedPoint> + Zero, FixedPoint: FixedPointNumber + FixedSignedCast<Signed = FixedI128>,

fn compute(&self, input: Asset, context: &PiecewiseConfig<FixedPoint>) -> Asset

Computes the model’s output for a given immutable input and context.