How to get Sum of “last” items of N hot Observable instances?

Question

EDIT: On 09/15/2013 - I am describing my scenario further broken into steps to help everybody understand my situation better. Added the source for whole application for down

Answer 1

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Anyway....

1 Do you want a running sum or just a single sum at the end?

2 Then, do you want a sum for all values for all streams, or the sums of each stream?

To get a single sum value for a sequence you use the .Sum() operator. http://introtorx.com/Content/v1.0.10621.0/07_Aggregation.html#MaxAndMin

To get a running total, use the Scan operator. http://introtorx.com/Content/v1.0.10621.0/07_Aggregation.html#Scan

So the answer is probably something like this (untested):

sources.Select(source=>source.Scan(0m, (acc, value)=>acc+=value)).Merge();