import type { TrendType } from '../types';
/**
 * 计算趋势方向
 *
 * @param comparison 环比数值
 * @returns 'up' | 'down' | 'neutral'
 *
 * @example
 * calculateTrend(120) // 'up'
 * calculateTrend(-230) // 'down'
 * calculateTrend(0) // 'neutral'
 * calculateTrend(null) // 'neutral'
 */
export declare function calculateTrend(comparison: number | string | null | undefined): TrendType;