Any Octave users? What is this code snippet actually doing?

[Joshua Judson Rosen]

Bruce Dawson <jbd at codemeta.com> writes:
>
> Write a review of the book and indicate that the code therein has bugs!
>
> You're the eyeball + 1. Strengthen your power by reporting the bug in a
> public forum! Help prevent others from falling into the same hole.

<favorite>.

Also, consider sending a picture of the page in question to this guy:

    http://thankstextbooks.tumblr.com/


> On 04/07/2013 10:35 AM, Bruce Labitt wrote:
> > On 04/06/2013 04:58 PM, Michael ODonnell wrote:
> >>> kmax=1;
> >>> kfactor=(kmax-1.0)/delta/(orderbc+1.0)/delbc^orderbc;
> >>> Unless matlab treats floats and ints differently than most other
> >>> languages, I'd say its a bug because zero over anything is always zero.
> >> Shame on anybody who'd intentionally code something like
> >> that without also providing a comment about such a seemingly
> >> counterintuitive approach.  >-/ Let's hope it's simply a bug...
> >>
> >> Out of morbid curiosity, how does Octave report the value of
> >> kfactor after
> >>
> >>     kmax=1
> >>     kfactor=(kmax-1.0)
> >>
> >>    ??
> >>   
> >> _______________________________________________
> >> gnhlug-discuss mailing list
> >> gnhlug-discuss at mail.gnhlug.org
> >> http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
> >>
> >>
> > kfactor = 0 is reported by octave in debug mode.
> >
> > That's a long bit of code
> >
> > kfactor=(kmax-1.0)/delta/(orderbc+1.0)/delbc^orderbc;
> >
> > just to set it to zero.  Clearly a bug, or just plain wrong and not 
> > thought through.  Drives me nuts, since this construct was used for the 
> > x, y, and z axes.
> >
> > Guess I'll have to contact one of the authors of the book.  The graduate 
> > student that wrote the code has since graduated.  (Got her PhD int 
> > 2010.)  Humph, you'd think the code samples for something this 
> > complicated would be better.
> >
> > \rant on
> > The level of commenting in the code sample is not up to teaching 
> > standards, IMHO.  If you are doing something tricky, write a descriptive 
> > comment on it!  (I can't even remember tricky stuff I did last week 
> > without good comments.)  Please, everyone, don't write ultra dense code 
> > like this, spaces are your friend!
> >
> > dx(:,2:je_tot,2:ke_tot)=C1ex(:,2:je_tot,2:ke_tot).* 
> > dx(:,2:je_tot,2:ke_tot)+ 
> > C2ex(:,2:je_tot,2:ke_tot).*((hz(:,2:je_tot,2:ke_tot)-hz(:,1:je_tot-1,2:ke_tot))-
> > (hy(:,2:je_tot,2:ke_tot)-hy(:,2:je_tot,1:ke_tot-1)))./delta;
> >
> > Especially if there are 5 more lines just like it, with slightly 
> > differing indices, with no spaces in between!
> > \rant off
> >
> > As you were.  :)
> >
> >
> >
> > _______________________________________________
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> > gnhlug-discuss at mail.gnhlug.org
> > http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
>
> _______________________________________________
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> http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
>

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