Creating an Exponential Decay

[Anonymous]

I am attempting to create a calculation that uses an exponential decay. In Excel, this is very easy since I can reference the cell that was calculated above the cell that is currently being calculated. Here is what it looks like in Excel.

Exponential Rate of Decay	0.6
Decay Calculation	=Current Balance * EXP(- Rate of Decay / 12)
Date	Balance
1/1/2016	100.00
1/2/2016	95.12
1/3/2016	90.48
1/4/2016	86.07
1/5/2016	81.87
1/6/2016	77.88
1/7/2016	74.08
1/8/2016	70.47
1/9/2016	67.03
1/10/2016	63.76
1/11/2016	60.65
1/12/2016	57.69

I have tried the above() function but it will not calculate the values. I am guessing since there is a calculation inside of a calculation it is getting lost. Here is the calc:

            above((Sum([Static Raw Value])/Sum([Static Number of Sites])/Sum([Static Number of Days In Month]))

            *exp(-.6/12))*exp(-0.6/12)

Anyone have any ideas? Any help would be appreciated.

[sunny_talwar · Accepted solution]

Like this?

[sunny_talwar]

or may be this where vDecay can be changed by the users

=Alt((Above(Expression) * Exp(-vDecay/12)), Value)

[Anonymous]

Sunny,

Thanks that worked perfectly. Qlik Sense gives an error on the expression but will execute with the correct answer anyway.

Thanks for the help.

Here is the final expression:

alt((above(Exponential))*exp(-.6/12),(Sum([Static Raw Value])/Sum([Static Number of Sites])/Sum([Static Number of Days In Month])))

FYI, "Exponential" is the name of the column that this expression resides in.