Espigah

// This function calculates the Periodic Payment (PMT) of a loan.
//  - rate: The interest rate per period (e.g., monthly interest rate for a monthly payment loan).
//  - periods: The total number of payment periods.
//  - value: The present value of the loan (amount borrowed).
//  - future: The future value at the end of the loan (usually 0 for a loan).
//  - ptype: Boolean indicating payment type (true for pay in advance, false for end of period).
func PMT(rate, periods, value, future float64, ptype bool) float64 {
    var payment float64
    if rate == 0 { // Handle special case: zero interest rate
        payment = (value + future) / periods  // Simple calculation for zero interest