From: <HIDDEN>
Newsgroups: comp.soft-sys.matlab
Subject: Re: differentiate
Date: Mon, 18 Oct 2010 01:12:04 +0000 (UTC)
Organization: The MathWorks, Inc.
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"mahshid " <> wrote in message <i9g5g3$ekp$>...
> Hi there,
> I have problem in differentiating an equation in my Matlab code, there is this error "Difference order N must be a positive integer scalar" when i use "diff" command to differentiate my Eq.
> could u pls tell how i can do it?
> tanx
- - - - - - - - - - -
  Show in detail how you call on 'diff' and we'll show you how your "difference order" argument (the second argument) is not a positive integer scalar.  Conceivably negative values could be interpreted as indefinite integrals (though they aren't,) but it is hard to visualize what a fractional order derivative might be.

Roger Stafford