sum of amounts based on period range in FAGLFLEXT

Dear Experts,

I have a requirement to add the amounts based on period range selected through selection screen. For examples in the the screen selection user selects Fiscal year , Fiscal Period_From and Period_To as

year ;2015

period_from: 001

period_to  : 008

then logic required is to sum the amounts HSL01 - till HSL08.

if user selects different range like period_from = 004 and period_to= 009 then sum (HSL04 till HSL09)

This logic is required to sum the amounts dynamically as user can select between 000 till 011. Please let me know how can this be done using graphical calculation view

Thanks in advance

pradyumna