Bivariate Poisson VBA

[clattenburg cake]

Hi, I'm trying to get Excel to calculate a part of a Bivariate Poisson function (mathematical formula attached as document). I have part of the formula I need, but I can't seem to get the right value using VBA- here is my code so far, but it doesn't look right:

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Can someone help please?

[jason_lee_91]

I think it might be because of where your k=0 is placed.
It should be outside the do until loop shouldnt it?
You initialize k as 0 then sum until min(x,y)

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[clattenburg cake]

I think it might be because of where your k=0 is placed.
It should be outside the do until loop shouldnt it?
You initialize k as 0 then sum until min(x,y)

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Hi, that solved my initial problem- however I don't think the values I'm getting are correct. For instance, using the function in my document, pbivpois(0,0) should be 1. However I am getting 0 instead...

[jason_lee_91]

That is because min(0,0)=0 and the do until loop terminates before the first iteration.
Try changing it to a Do While <= min(x,y)

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[clattenburg cake]

That is because min(0,0)=0 and the do until loop terminates before the first iteration.
Try changing it to a Do While <= min(x,y)

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Cheers, it seems to work once I move the pbivpois=0 out of the "do while" loop! Thanks a lot for the help. This is the final answer:

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[jason_lee_91]

Ah!
Haha I cant believe I moved the k=0 out but forgot to move the pbivpois=0.
Cool piece of code though.
Seems like a neat project your working on

[schmoopies]

Thanks for working through that - I have been playing with Bivariate Poisson for some time and your code is VERY helpful
Cheers