[ncl-talk] bug report stddev (build-in function)

[Kampenhout, L. van (Leo)]

Hi,

I just stumbled upon the following inconsistency. In the description of function stddev it is written that (http://www.ncl.ucar.edu/Document/Functions/Built-in/stddev.shtml)

  (…) this function calculates the population standard deviation.

However, I’m afraid it does not compute the population std but rather the sample std. Example program attached.

I see two solutions:
(1) either change the documentation, such that is states specifically this function computes the sample standard deviation (perhaps also add an explanation why this is better).
(2) change the code . This will create a backward incompatibility and many user scripts may yield different results.

As a side note, function stdMonTLL also computes the sample std, second example program attached.

Kind regards,
Leo



____________________________________________________________

Leo van Kampenhout
Institute for Marine and Atmospheric Research (IMAU), Utrecht University
BBG room 672
Princetonplein 5, 3584 CC Utrecht, The Netherlands
+31 30 2533271
L.vanKampenhout at uu.nl<mailto:L.vanKampenhout at uu.nl>
www.uu.nl/wce<http://www.uu.nl/wce>


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150128/8285497e/attachment.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: stdMonTLL_driver.ncl
Type: application/octet-stream
Size: 464 bytes
Desc: stdMonTLL_driver.ncl
Url : http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150128/8285497e/attachment.obj 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: stddev_driver.ncl
Type: application/octet-stream
Size: 461 bytes
Desc: stddev_driver.ncl
Url : http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20150128/8285497e/attachment-0001.obj