From: ddoherty03 <ddoherty03@...>
Date: 2009-07-24T00:00:05+09:00
Subject: Re: Bug Rounding Floats? (9.245 * 100).round => 924? S/B 925!

On Jul 23, 9:37 am, Glenn Jackman <gle...@ncf.ca> wrote:
> At 2009-07-22 03:22PM, "ddoherty03" wrote:
>
>
>
> >  On Jul 22, 1:13 pm, Glenn Jackman <gle...@ncf.ca> wrote:
> > > A workaround, convert the expression to a string and back to a number:
> > >     num = Float("%.1f" % (9.245 * 100)).round
> > >     puts "yippee" if num == 925
>
> >  Glenn,
>
> >  Thanks for the explanation.  If I could pick your brain for a second
> >  on how to generalize your workaround, I would greatly appreciate it.
>
> >  Here is how I tried to implement the "nround" method.
>
> >  ######################################
> >  class Float
> >    def nround(n = 0)
> >      (self * 10.0 ** n).round / 10.0 ** n
> >    end
> >  end
> >  ######################################
>
> >  My issue is getting the workaround to deal with the parameter n
> >  properly.
>
> Taking Bil Kleb's advice,
>
>     require 'bigdecimal'
>     require 'bigdecimal/util'
>
>     class Float
>       def nround(n=0)
>         (self.to_d * (10.0**n).to_d).round.to_f / 10.0**n
>       end
>     end
>
>     p 9.245.nround(2)  # => 9.25
>
> --
> Glenn Jackman
>     Write a wise saying and your name will live forever. -- Anonymous

Bil & Glenn & Thomas,

Thanks.  Performance is not a problem, so this works for me.

Much appreciated.