Trouble with Syntax for recursive function that runs until a loan balance reaches 0

Question

SA=1000.00

AI=0.12

MP=100.00

def remainb(x):

if x==0:

    return 0

else: 

    return

    x=(SA+(AI/12)*SA)-MP

    for i in range(x,1000000):

        x=(x+(AI/12)*x)-MP

        CIwoP=(x+(AI/12)*x)-x #interest every month

        ptd=MP*i#payment to date

        #ptdreal=(ptd-CIwoP)

        #rbal=(CIwP-ptd)

        print(i)#payment no.

        print(ptd)#amount paid to date

        print(CIwoP)#interest for that month

        print(x)#balance for each month after payment

        #if rbal==0: return 0

        #return 

Made multiples attempts at debugging but failed repeatedly for hours. Frankly, I am stuck. If anyone can give me any advice on how to approach this problem (eg. run the loop until SA==0).

Answer 1

You are trying to Switching to while loop is more appropriate as you are not sure how many times you need to loop. This will continue as long as x greater than 0.

x = (SA + (AI / 12) * SA) - MP

payment_number = 0

while x > 0:

    x = (x + (AI / 12) * x) - MP

    CIwoP = (x + (AI / 12) * x) - x  # interest every month

    ptd = MP * payment_number  # payment to date

    payment_number += 1

    print(payment_number)  # payment no.

    print(ptd)  # amount paid to date

    print(CIwoP)  # interest for that month

    print(x)  # balance for each month after payment

Recursion approach

def remainb(x, payment_number=0):

    if x < 0: return

    x = (x + (AI / 12) * x) - MP

    CIwoP = (x + (AI / 12) * x) - x  # interest every month

    ptd = MP * payment_number  # payment to date

    payment_number += 1

    print(payment_number)  # payment no.

    print(ptd)  # amount paid to date

    print(CIwoP)  # interest for that month

    print(x)  # balance for each month after payment

    remainb(x, payment_number)

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