Pmt  script and chart function
This function returns the payment for a loan based on periodic, constant payments and a constant interest rate. It cannot change over the life of the annuity. A payment is stated as a negative number, for example, 20.
Pmt(rate, nper, pv [ ,fv [ , type ] ] )
Return data type: numeric. The result has a default number format of money. .
To find the total amount paid over the duration of the loan, multiply the returned pmt value by nper.
Arguments:
Argument  Description 


The interest rate per period. 

The total number of payment periods in an annuity. 
pv 
The present value, or lumpsum amount, that a series of future payments is worth right now. If pv is omitted, it is assumed to be 0 (zero). 
fv 
The future value, or cash balance, you want to attain after the last payment is made. If fv is omitted, it is assumed to be 0. 
type 
Should be 0 if payments are due at the end of the period and 1 if payments are due at the beginning of the period. If type is omitted, it is assumed to be 0. 