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You could.. multiply the average register by the count register, then add the new integer to the average register, increment the count register and then re-divide?

How about a special running average: keep the count in one register and the average in the other one. Let's say N is the current count and av the average. The algorithm is in C-style notation: void addElement( int val ) { ++N; av = ((N - 1) * av / N) + val / N; }

I have used a similar trick (with a fixed N) to implement a cheap running average for an image acquisition software and it works quite well, but of course if N is very large val / N becomes negligible.

You guys are so goddamn geeky! <3

constant space ftw

Let average-so-far=a, count=c. When you add a new item x, the new average is: a = a + (x-a)/(c+1)

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