[ADMB Users] Question about R2admb

John Sibert sibert at hawaii.edu
Mon Mar 31 14:10:50 PDT 2014

This seems like a really good idea to me. It is a much better way to 
implement a step function or threshold functional relation than trying 
to fart around with various types of sigmoid approximations that may be 
hard to estimated.

John Sibert
Emeritus Researcher, SOEST
University of Hawaii at Manoa
Honolulu HI (GMT-10)

Visit the ADMB project http://admb-project.org/

On 03/30/2014 08:06 AM, dave fournier wrote:
> I'm not sure exaclty what is wanted, but it does suggest  that one may 
> want something like the following function
> which I suppose could get added to ADMB in some form.
> It should be
>                        a if x<=c-e
>            f(x) =
>                        b if x>=c+e
>            f'(x-e)=0
>            f'(x+e)=0
>          f is nice for c-e<x<c+e
> this can be done with a cubic spline.   A nice way is to
> declare a class to hold the necessary information and a function 
> object or functor
> to evaluate the function .  It could be extended to deal with more 
> general boundary
> conditions
>           f'(x-e)=u
>           f'(x+e)=v
> with a bit of care.
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