On Feb 4, 9:51 am, Spon <christoph.b...@[EMAIL PROTECTED]
> wrote:
> On Feb 4, 2:31 pm, cmanc...@[EMAIL PROTECTED]
wrote:
>
>
>
> > On Feb 4, 9:29 am, cmanc...@[EMAIL PROTECTED]
wrote:
>
> > > I'm having an error in my code and I stop it to check out what is
> > > going on. Here's the three relevant lines of code:
>
> > > minmag = min(sims[mag,*],max=maxmag)
> > > nbins = (maxmag-minmag)/magbinsize
> > > magres = fltarr(3*nfilters,nbins)
>
> > > Here's some commands I type into a command line to investigate my
> > > issues:
>
> > > IDL> help,nbins
> > > NBINS FLOAT = 7.00000
> > > IDL> help,magres
> > > MAGRES FLOAT = Array[6, 6]
>
> > > Anyone see a problem here? nbins is a float of size 7.0, and yet
> > > magres ends up with 6 rows!!!! To add to the fun I then type the
> > > following:
>
> > > IDL> nbins = 7.0
> > > IDL> magres = fltarr(3*nfilters,nbins)
> > > IDL> help,magres
> > > MAGRES FLOAT = Array[6, 7]
>
> > > To summarize, my array is created with the wrong dimensions, so I
re-
> > > assign one of the variables with the exact same value that it had
> > > before, recreate my array, and it works! ?????? Looks like a bug to
> > > me...
>
> > And in case anyone thinks this might be part of the problem:
>
> > IDL> help,nbins
> > NBINS FLOAT = 7.00000
> > IDL> help,nfilters
> > NFILTERS LONG = 2
> > IDL> magres = fltarr(3*nfilters,long(nbins))
> > IDL> help,magres
> > MAGRES FLOAT = Array[6, 6]
>
> help,fltarr(6,6.99)
> <Expression> FLOAT = Array[6, 6]
>
> nbins = (maxmag-minmag)/magbinsize
> If this ever returns a value just under 7.00000 it'll always be
> rounded down when it's converted . I suspect this is what's happening
> to you.
>
> To test it, you could try:
> magres = fltarr(3*nfilters,round(nbins))
>
> Does this fix your problem?
> Chris
Arrgh!! I should have seen that one coming, I've read that article
before and have even explained to others the dangers of floating-point
representation. Oh well. Thanks for the help guys!
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