How are you calcing standard deviation in Excel? There's STDEV, STDEVA, STDEVP, STDEVPA, off the top of my head.

Excel's STDEVP uses the n-1 as the denominator, so you should probably use 

my $elements = $#ar;

[download]
just to compare apples and apples.
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jpg

In reply to Re: standard deviation accuracy question by jpeg
in thread standard deviation accuracy question by Anonymous Monk

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