Re: Integration with quad

[David Bateman]

address@hidden wrote:
> -----Original Message-----
> From: Søren Hauberg [mailto:address@hidden 
>
> ons, 09 12 2009 kl. 20:07 +0100, skrev Thomas Göbel:
>   
> > > i want to integrate the following function:
> > >
> > > function y = rect(t)
> > > if t<=0.5
> > >     rect=1
> > > else
> > >     rect=0
> > > end
> > > endfunction
> > >       
>
>   
> > Your return value is called 'y', but you never define this in your
> > function. Try something like
> >
> > function y = rect(t)
> >  if t<=0.5
> >    y=1
> >  else
> >    y=0
> >  endif
> > endfunction
> >     
>
> You can also write:
>
> function y = rect(t)
>   y = (t<=0.5);
> endfunction
>
> This function will work on a vector.  Are there methods to "vectorize" other 
> functions with less tractable conditional statements?
>
> Regards,
> Allen
>   
Yes quadgk or quadv is what you are looking for.. It also has another 
advantage in that it handles infinite limits, boundary singularities and 
you can define point of discontinuities in the function or its derivatives
with the "WayPoints" options (if you know them) like

quadgk ('rect', -1, 2, 'WayPoints', 0.5)

Also, using an anonymous function handle like

quadgk(@(x) rect(x), -1, 2, 'WayPoints', 0.5)

will certainly be faster in the development sources, though probably not 
in 3.2

D.