/**
 * Calculate Net Present Value (NPV) of cash flows
 *
 * NPV = Σ(CF_i / (1 + r)^t_i)
 *
 * @param cashFlows - Array of cash flows (positive for inflows, negative for outflows)
 * @param timePeriods - Array of time periods in years corresponding to each cash flow
 * @param rate - Discount rate (as decimal, e.g., 0.1 for 10%)
 * @returns Net Present Value
 */
export declare function calculateNPV(cashFlows: number[], timePeriods: number[], rate: number): number;