From: Jason Roelofs <jameskilton@...>
Date: 2007-12-05T21:33:50+09:00
Subject: Re: what's wrong with these calculations?

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On Dec 5, 2007 6:54 AM, hemant <gethemant@gmail.com> wrote:

> On Dec 5, 2007 5:22 PM, hemant <gethemant@gmail.com> wrote:
> > On Dec 5, 2007 5:00 PM, Ivo Dancet <caifara.subscribe@gmail.com> wrote:
> > > Hi
> > >
> > > I thought, why search for two hours being totally frustrated if I can
> > > just ask...
> > >
> > > why does this happen:
> > >
> > >  >> 73.07-63.00
> > > => 10.07 # ok, normal!
> > >  >> 73.07-64.00
> > > => 9.06999999999999 # why oh why?
> >
> > Thats folly of floats, you can't do much apart from :
> >
> > sprintf("%.2f",(73.07-64.00)).to_f
> >
>
> generally, I add a method to Float class like this:
>
> class Float
>  def r2p places
>    sprintf("%.#{places}f",self).to_f
>  end
> end
>
>
Also look into using the BigDecimal class. It does special processing to
keep floating point precision.

Jason

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