Σ series solution

[#1]

Hi,

I have a partial sum series to resolve.

Y = Σ x/(1+b)^i

Where the partial sum (Σ) is from i =1 to n. i  varies between 1 to 25 depending on the record. Basically all of the terms of the equation are known except for y.

What functions could I use to calculate this in a chart, or failing that, in the script?

Thanks,

Mike

[#2]

Could you post a sample dataset?

[#3]

Hi Borja,

Thanks for the reply and sorry about my absence.

An example dataset would simply be:

Load * Inline

[

Y,b,i

85000,0.08,12

125000,0.05,8

75000,0.02,20

100000,0.1,10

];

Essentially these are parameters for NPV. I am missing the payments and want to extrapolate them using the other terms. Y is the NPV, b is the discount, and i is the life of the loan. I can do this mathematically outside of qlik but cant work out a way to do it in a Qlik load script.

Thanks for the attention to this problem.

Mike