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Re: problems with FindRoot: what worked with 4.2 does not work with 5.0


The usual fix for us is to modify the functions so that they only execute 
for numerical input. This can be done by placing a NumberQ conditional with 
some or all of the input arguments. I'm guessing that without the 
conditional, FindRoot now attempts a symbolic derivative, and fails if you 
have a complex function (like anything containing an If statement).

Gerry Flanagan


At 06:36 AM 4/6/2004, Edgar Dachs wrote:
>Computers & Geosciences, 24/3: 219-235) und worked out a
>new version that I tested with Mathematica version 4.2. With 5.0, I now
>find problems that several of my functions do not work any more,
>obviously do to changes that have been employed between 4.2 and 5.0
>concerning FindRoot.
>Below is a little test-function that illustrates the problem: the
>return-value of the function depends on the value of x, as in the much
>more complex petrological functions that I have written, where
>calculations depend e.g. on the value


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