Re: Output function

[Juan Pablo Carbajal]

On Tue, Sep 27, 2011 at 4:27 PM, c. <address@hidden> wrote:
>
> On 27 Sep 2011, at 16:09, Juan Pablo Carbajal wrote:
>
>> Hi all,
>>
>> I want to generate a function that retruns a function. Example
>> t=linspace(0,1,100);
>> y = sin(2*pi*t);
>> func = data2fun(t,y)
>>
>> where data2func looks like
>>
>> function f = data2fun (t, y)
>> pp = spline (t, y);
>> f = @(t_) ppval (pp, t_);
>> end
>
> why do you need a function to return the function?
> I think this does what you want:
>
> fun_gen = @(x, t, y) ppval (spline (t, y), x);
> fun = @(x) fun_gen(x, t, y);
>
> but maybe the following is more efficient as it does not recompute the 
> polynomial every time:
>
>
> fun_gen = @(pp, y) ppval (pp, x);
> pp = spline (t, y);
> fun = @(x) fun_gen(pp, y);
>
>
>> Is there a better way to do it?
>>
>> Thanks
>>
>> --
>> M. Sc. Juan Pablo Carbajal
>> -----
>> PhD Student
>> University of Zürich
>> http://ailab.ifi.uzh.ch/carbajal/
>> _______________________________________________
>> Help-octave mailing list
>> address@hidden
>> https://mailman.cae.wisc.edu/listinfo/help-octave
>
>

Thank you Carlo,

I want to hide the interpolation from the usage of the function unless
the user wants to specify how to do the interpolation.
Fro example, in optimal control problems, the optimal controller
sometimes is given as data points (direct collocation methods, for
example). But to use it in an ode simulation one would need an
interpolating function. Instead of writing the three 2 lines you
suggest, one could just call data2fun. Is really a wrapper of what you
are doing.
Is it better to return an inline of a handle, or is there another way
(a string?)?



-- 
M. Sc. Juan Pablo Carbajal
-----
PhD Student
University of Zürich
http://ailab.ifi.uzh.ch/carbajal/