| Huh?? Stddev went crazy! [message #59858] |
Wed, 16 April 2008 12:07 |
Conor
Messages: 138
Registered: February 2007
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Senior Member |
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I'd like to see someone explain this one. My stddev function
apparently lost all grasp on reality?
IDL> print,stddev([1,2,3,4,5])
3.07421 3.24566 3.08206 3.26360 2.97446
IDL> print,stddev([1.,2.,3.,4.,5.])
3.07421 3.24566 3.08206 3.26360 2.97446
IDL> print,stddev([1.,2.])
3.07421 3.24566
IDL> print,stddev(findgen(32))
2.99513 3.07421 3.24566 3.08206 3.26360
2.97446 2.96850 3.04474 2.66875 2.77181
2.83465
2.77395 2.77370 2.87829 2.84716 2.86982
2.98503 2.93160 2.77602 2.59318 2.83169
3.30869
2.67353 3.15337 3.19076 3.19499 2.96050
3.13871 2.61707 2.77854 3.12603 3.20029
Finally I did this:
IDL> .reset
And it returned to normal! Yeah!
IDL> print,stddev(findgen(32))
% Compiled module: STDDEV.
% Compiled module: MOMENT.
9.38083
IDL> res = findgen(10,10)
IDL> print,stddev(res)
29.0115
I have not been able to reproduce the crazy behavior since (not that
I've tried very hard). Still, it's rather worrisome if the behavior
of a built in function isn't reliable!!
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