[Haskell-cafe] cumulative sum
Tamas K Papp
tpapp at Princeton.EDU
Mon Oct 2 12:03:05 EDT 2006
Hi,
I have two lists, p and lambda (both are finite). I would like to
calculate
1) the cumulative sum of lambda, ie if
lambda = [lambda1,lambda2,lambda3,...]
then
csum lambda = [lambda1,lambda1+lambda2,lambda1+lambda2+lambda3,...]
2) the cumulative sum of p*lambda (multiplication elementwise)
Once I know how to do the first, I know how to do the second I guess
(doing the multiplication using zipWith to get the p*lambda list, but
I would be interested in any other suggestions). Currently I take and
sum, but then I am calculating the same sums many times.
Thanks,
Tamas
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