/**
 * Linear easing function.
 * @param ratio
 */
export declare function easeLinear(ratio: number): number;
/**
 * easeOutQuad.
 * @param ratio
 */
export declare function easeOutQuad(ratio: number): number;
/**
 * easeOutCubic.
 * @param ratio
 */
export declare function easeOutCubic(ratio: number): number;
/**
 * easeOutQuart.
 * @param ratio
 */
export declare function easeOutQuart(ratio: number): number;
/**
 * easeOutBack.
 * @param ratio
 */
export declare function easeOutBack(ratio: number): number;
/**
 * Easing function.
 */
export interface Easing {
    (ratio: number): number;
}
/**
 * Returns an easeOut function.
 * @param exponent - Integer from 1 to 4.
 */
export declare function getEasingFunction(exponent: number): Easing;