compound interest calculation with regular deposits over different periods
I am putting together a calculator which does compound interest calculation with regular deposits over different periods.
Full html code in text format below is of working solution based upon changing all periods to weekly and calculating totals weekly. However I want to instead of doing it this way have different periods calculated only in their respected period length ie if 4 year selected than the inflated amount is only added every 4 years.
Basically I want pic 1 to look like pic 2 or excel attachment
Can someone please please help me im am stuck with how to do this.
Thank you in advance