Averages/Root mean square: Difference between revisions

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<lang PL/I>
<lang PL/I>
declare A(10) fixed decimal static initial (1,2,3,4,5,6,7,8,9,10);
declare A(10) fixed decimal static initial (1,2,3,4,5,6,7,8,9,10);
RMS = sqrt(sum(a**2))/n;
RMS = sqrt(sum(a**2)/n);
</lang>
</lang>



Revision as of 13:51, 21 February 2010

Task
Averages/Root mean square
You are encouraged to solve this task according to the task description, using any language you may know.

Compute the Root mean square of the numbers 1..10.

The root mean square is also known by its initial RMS (or rms), and as the quadratic mean.

The RMS is calculated as the mean of the squares of the numbers, square-rooted:

C.f. Averages/Pythagorean means

Lua

<lang lua>function sumsq(a, ...) return a and a^2 + sumsq(...) or 0 end function rms(t) return (sumsq(unpack(t)) / #t)^.5 end

print(rms{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})</lang>

PL/I

<lang PL/I> declare A(10) fixed decimal static initial (1,2,3,4,5,6,7,8,9,10); RMS = sqrt(sum(a**2)/n); </lang>

Python

<lang Python>>>> from __future__ import division >>> from math import sqrt >>> def qmean(num): return sqrt(sum(n*n for n in num)/len(num))

>>> numbers = range(1,11) # 1..10 >>> qmean(numbers) 6.2048368229954285</lang>