[Numpy-discussion] Distribution Functions Change Behavior

Rich Shepard rshepard@appl-ecosys....
Mon Apr 28 08:13:19 CDT 2008


   AFter the extensive input from folks here last week, and my examination of
alternatives, I accepted the visual appearance of Gaussian curves in our
model. As I check the plots for data errors I find a behavior change when
the x-axis length is 14 rather than 100, and I do not understand why.

   I would appreciate the ideas of the mathematically adroit here to help
resolve the problem. However, if this is not the appropriate forum for such
a discussion, please point me to the more appropriate one.

   Most of the plots cover a range of independent values of 0-100. Some are
greater (e.g., 0-1,000 or 0-10,000). However, for pH the range is 0-14. The
plots for pH do not consist of sigmoid curves (a 'Z-curve' from 0-7 and an
'S-curve' from 7-14); they are straight lines. The Gaussian curve does not
approach zero on either end (0 or 14).

   I can provide the functions for these curves.  I need to understand why
the results change when the range of the independent variable is short and
learn how to produce correct results.

Rich

-- 
Richard B. Shepard, Ph.D.               |  Integrity            Credibility
Applied Ecosystem Services, Inc.        |            Innovation
<http://www.appl-ecosys.com>     Voice: 503-667-4517      Fax: 503-667-8863


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