# Thread: Root Mean Square--Does it exist? (2000)

1. ## Root Mean Square--Does it exist? (2000)

I need to regularly do an analysis of a large file of data, finding the RMS (Root Mean Square) of the results. Does this function exist in Excel, or is there an easy way of doing it?

Currently I have to add a column, and square the values from the original column. Then I have to sum those values, divide by the number of values (thanks to the COUNT feature, at least I don't have to do that calculation) and take the square root of that value.

2. ## Re: Root Mean Square--Does it exist? (2000)

Excel has a SUMSQ function that computes the sums of the squares of the arguments. So if your data are in A1:A10, the following formula computes the RMS without intermediate columns:

=SQRT(SUMSQ(A1:A10)/COUNT(A1:A10))

3. ## Re: Root Mean Square--Does it exist? (2000)

<P ID="edit" class=small>(Edited by sdckapr on 29-Oct-03 13:08. Forgot the sqr root)</P>If your values are in A1: A100, the array (confirm with ctrl-shift-enter):

=sqrt(AVERAGE(A1:A100*A1:A100))
or
=sqrt(AVERAGE(A1:A100^2))

should work. Change range as appropriate. I always heard (in BASIC days) it was more efficient to use X*X rather than X^2 since it was a simpler routine, but I leave them both for you.

Steve

4. ## Re: Root Mean Square--Does it exist? (2000)

Well, blow me down!! I had pawed through Excel and I thought I had examined all of the functions. Thank you.

(Incidentally I really am not a "new lounger" as I have been lurking for ages. I just haven't seen the need to ask for help. I also don't stop to ask for directions either!!!)

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