import type { NumberArray } from 'cheminfo-types';
import type { CalculateAdaptiveWeightsOptions } from '../utils/index.ts';
export interface XWhittakerSmootherOptions extends CalculateAdaptiveWeightsOptions {
    /**
     * Factor of weights matrix in -> [I + lambda D'D]z = x
     * @default 100
     */
    lambda?: number;
    /**
     * Maximum number of iterations for the baseline refinement process.
     * @default 100
     */
    maxIterations?: number;
    /**
     * Tolerance for convergence. The process stops if the change in baseline is less than this value.
     * @default 1e-6
     */
    tolerance?: number;
    /**
     * Learning rate for weight updates.
     * @default 0.5
     */
    learningRate?: number;
    /**
     * Solver algorithm to use for the smoothing routine.
     * - `'cholesky'` — build the full (symmetric) system and solve using a
     *   Cholesky decomposition. Generally more robust for small/medium arrays
     *   and when a matrix factorization is acceptable.
     * - `'thomas'` — use a tridiagonal formulation and solve with the Thomas
     *   algorithm (specialised tridiagonal solver). Lower memory usage and
     *   faster for large inputs when the system is tridiagonal.
     * @default 'thomas'
     */
    algorithm?: 'cholesky' | 'thomas';
}
export declare function xWhittakerSmoother(yData: NumberArray, options?: XWhittakerSmootherOptions): Float64Array<ArrayBuffer>;
/**
 * @deprecated Use xWhittakerSmoother instead.
 * TODO: Remove in next major version.
 */
export declare const xWhitakerSmoother: typeof xWhittakerSmoother;
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