Re: quadl crashes on evaluation

[Ben Abbott]

On Sep 20, 2008, at 1:07 PM, rmcd wrote:
> David Bateman-3 wrote:
> > It shouldn't crash as the issue here is only that the recursion  
> > limit of
> > Octave is met. I suspect that cygwin doesn't like a 256 deep  
> > recursion
> > as set by default with Octave and you should try something like
> >
> > max_recursion_depth (128)
> > quadl (@(x) x .* sin (1 ./ x) .* sqrt (abs (1 - x)), 0, 3)
> >
> > and see if it still crashes. If it doesn't, I'd suggest that the  
> > cygwin
> > maximum recursion depth be reduced.
>
> You're correct. Octave does not crash if I set max_recursion_depth  
> to 128.
>
> If I could ask another question about this example, the first time I  
> call
> quadl I get the following errors (this doesn't happen with quad and  
> only the
> first time with quadl):
>
> octave:1> quadl ("f",0,3)
> error: `x' undefined near line 2 column 5
> error: evaluating binary operator `.*' near line 2, column 7
> error: evaluating binary operator `.*' near line 2, column 23
> error: evaluating assignment expression near line 2, column 3
> error: called from `f' in file `/cygdrive/d/progdata/matlab/rmcd/ 
> test/f.m'
> error: evaluating argument list element number 1
> error: evaluating assignment expression near line 126, column 5
> error: called from `quadl' in file
> `/usr/share/octave/3.0.2/m/general/quadl.m'
>
> The function file looks like this:
>
> function y = f (x)
> y = x .* sin (1 ./ x) .* sqrt (abs (1 - x));
> endfunction
>
> It seems to be some kind of initialization error. Not a big deal,  
> but I'm
> curious.

I'm able to run 3.0.1 and 3.1.51 (developers sources).

I don't see this error in either.

What happens when  you include the "eps" and the tolerance

> function y = f (x)
> y = x .* sin (1 ./ (x+eps)) .* sqrt (abs (1 - x));
> endfunction

        quadl ("f", 0, 3, 0.0001)

If still present, what of

        quadl (@f, 0, 3, 0.0001)

Ben