/**
 * Interpolation and smoothing utilities for color palette generation
 */
import { Effect } from "effect";
import type { TransformationPattern } from "../pattern/pattern.js";
declare const InterpolationError_base: new <A extends Record<string, any> = {}>(args: import("effect/Types").Equals<A, {}> extends true ? void : { readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }) => import("effect/Cause").YieldableError & {
    readonly _tag: "InterpolationError";
} & Readonly<A>;
/** Error when interpolation or smoothing operations fail */
export declare class InterpolationError extends InterpolationError_base<{
    readonly message: string;
    readonly cause?: unknown;
}> {
}
/** Degrees to radians conversion factor */
export declare const DEG_TO_RAD: number;
/** Radians to degrees conversion factor */
export declare const RAD_TO_DEG: number;
/**
 * Smooth the transformation pattern to ensure:
 * - Lightness is perfectly linear
 * - Chroma follows a smooth curve
 * - Hue is consistent (circular mean value)
 */
export declare const smoothPattern: (pattern: TransformationPattern) => Effect.Effect<TransformationPattern, InterpolationError>;
/** Linear interpolation between two values */
export declare const lerp: (a: number, b: number, t: number) => number;
/** Clamp a value between min and max */
export declare const clamp: (value: number, min: number, max: number) => number;
/**
 * Calculate circular mean of angular values (handles wraparound at ±180°)
 *
 * Standard circular mean: convert angles to unit vectors, average, convert back.
 * This correctly handles values clustered around the ±180° boundary.
 *
 * For example:
 * - circularMean([-175, 175]) ≈ 180 (not 0)
 * - circularMean([10, 20, 30]) = 20 (same as linear mean)
 *
 * @param angles - Array of angles in degrees
 * @param onEmpty - Function to create error when array is empty
 */
export declare const circularMeanWith: <E>(angles: ReadonlyArray<number>, onEmpty: () => E) => Effect.Effect<number, E>;
export {};
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