[proFit-list] Fitting Functions and Return Values

[pro Fit Support]

Dear Andrew

These are good questions.

1) If you really have a true "step function", i.e. something like
    if x > 0 then y := 1
    else y := -1;
then the correct derivative would, theoretically, be
    if x = 0 then y := inf
    else y := 0;
It is another question if fitting such a function will return a  
reasonable result. It very much depends on what your parameters are.

2) It is true that functions defined within a program cannot return an  
array, nor can arrays be used as var parameter. To circumvent this  
limitation, you either have to pass the array's elements (if the array  
is short enough) as individual var parameters, or you have to use a  
globally defined array for passing data back from your local function/ 
procedure. The latter is, in most situations, probably the better  
solution.


Best regards

Kurt Sutter
QuantumSoft



On 20.01.2009, at 18:36, Andrew Cameron Beveridge wrote:

> I am using proFit 6.1.10 and OS X 10.4.11.
>
> I have a couple of questions:
>
> I am batch processing a large number of files so any speed improvement
> would be welcome.
>
> I am fitting my files with a user-defined function that contains  
> Unit Step
> functions, ie, Heaviside step functions. I would to to add the  
> procedure
> Derivatives to my function. The derivatives of the step function are  
> dirac
> delta functions, which is really a distribution.
> 1.) Any ideas on how to program a dirac delta function in proFit  
> that can
> be used with the derivatives procedure?
>
> 2.) It appears that functions defined within a program cannot return  
> an
> array as a value. Is there any way around this? Can you return a  
> vector
> and get individual components out of the vector?
>
> Thanks for your help.
>
> Regards,
> Andrew
>
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