Sum the Product of Two quantities

I'm trying to sum (11-x)*poisspdf(x,90/13) from 0 to 11, however when I put the following in matlab it gives me several errors including x = double(x)

 sum((11-x)*poisspdf(x,90/13),x,0,11)

Answer 1

[Geoff Hayes]

Shane - does x range from 0 to 11? I think that you are trying to use sum to do that but that is not how this function can be used (please see the documentation as to why). What you can try is to do the following

 poissDistSum = 0;
 for x=0:11
     poissDistSum = poissDistSum + poisspdf(x,90/13);
 end

I suspect that you could also try the simpler

 X = 0:11;
 poissDistSum = sum(poisspdf(X,90/13));

[Walter Roberson]

x = 0:11;
sum((11-x).*poisspdf(x,90/13))

[Geoff Hayes]

Right! I forgot the (11-x)..