Re: [F-Script-talk] F-Script-talk] Adding Math Methods to Arrays

[Philippe M. <pm...@ac...>]

Peter,

You'll not need to modify the existing F-Script source code. The  
system is extensible and you can achieve what you want in a modular  
way by putting your code in Objective-C categories that you can build  
as separate bundles and load dynamically if you want.

For method that deal with whole arrays (i.e., that have no meaning for  
single numbers; e.g. calculating an average value given an array of  
numbers), you should first implement your method in a category of  
NSArray, in order to deal with the situation where you'd have an array  
of NSNumber objects. See for instance how the method "reverse" is  
implemented in F-Script's FSNSArray category. In your case you'll also  
need to make sure you raise an error if objects other that NSNumbers  
are found in the array. Then, if you want to have optimized  
implementations for situations where F-Script is able to determine  
that the array is made of numbers, you should add little stubs in a  
category of Array (again, for an example, see how the "reverse" method  
is implemented in the Array class) as well as your optimized  
implementations in a category of ArrayRepDouble (see how the "reverse"  
method is implemented in the ArrayRepDouble class).

For math methods that make sense on single numbers (like cos, sin,  
abs, etc.), you should first implement your method on single number  
objects. To do that, implement them for NSNumber objects in your own  
category of NSNumber (look at FSNSNumber for examples). Note that, at  
this point, you automatically get array programming for these methods.  
F-Script will take care of automatically broadcasting messages when  
you deal with arrays. In general this is fast enough. If you need to  
go even faster, you can implement optimized versions of your methods  
in a category of ArrayRepDouble. You'll just have to add  
simpleLoop_xxx or doubleLoop_xxx methods in your category (depending  
on the message pattern your math operation supports). See  
ArrayRepDouble.m for example of implementing these simpleLoop_xxx and  
doubleLoop_xxx methods.

Feel free to ask for further clarifications if needed.

Philippe

Le 23 juin 08 à 19:29, Peter A Passaro a écrit :

>
> Hi Philippe and All,
>
> I'm starting to work my way through the F-Script framework code, and
> the first thing I would like to do is add some additional math
> operators to the ArrayRepDouble class. Could you possibly give me a
> quick overview of the framework classes I will need to modify in order
> for this to work properly?
>
> Specifically, what I would like to add is a bunch of statistics and
> vector operations for arrays of doubles. I have been writing Obj-C
> wrappers (or alternative functions) for many of the functions in the
> GNU Scientific Library, and I would like to bring these into F-Script
> so I can avoid the back and forth conversion of arrays of doubles-
>> NSNumbers->doubles.
>
> I may also be interested in contributing a plotting/graphing
> application for arrays of doubles to F-Script, I have one I am
> developing for visualizing large time series data sets that will
> probably work well. Let me know if this might be interesting.
>
> Best,
> Peter
>
> Peter Passaro
> Research Officer
> Dept of Informatics/Dept of Biology
> Pevensey III
> University of Sussex
> Falmer, Brighton BN1 9QH, UK
> Office + 44 (0)1273 877590
> P.A...@su...
>
>
>
>
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