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RE: st: Re: a question on function int


From   "Jian Zhang" <jzh@ucdavis.edu>
To   Michael Blasnik <michael.blasnik@verizon.net>, statalist@hsphsun2.harvard.edu
Subject   RE: st: Re: a question on function int
Date   Thu, 20 Oct 2005 05:43:40 -0700 (PDT)

It is really helpful! Thanks, Michael!

Jian


> It has nothing to do with the int() function, it has to do with 
precision.
> 
> temzzz does not contain .005, but instead 0.0049999998882....  Try -
search
> 
> precision- and check out the various FAQs at the end to learn more.   
You
> 
> can sometimes address these problems by using doubles instead of 
floats. 
> In 
> other cases you can use the float() function and sometimes just using 
> round() works.  In your case, I would keep long integer IDs as string 
> variables to avoid precision issues and allow easier access to 
extracted 
> segments.
> 
> Michael Blasnik
> michael.blasnik@verizon.net
> 
> ----- Original Message ----- 
> From: "Jian Zhang" <jzh@ucdavis.edu>
> To: <statalist@hsphsun2.harvard.edu>
> Sent: Wednesday, October 19, 2005 4:30 PM
> Subject: st: a question on function int
> 
> 
> > Hello,
> >
> > I have a question about the function int that I could not understand
> what
> > stata is doing.  Hope that you can answer me.  Thanks.
> >
> > Here it is:
> >
> > For example, I have a data set:
> > id
> > 10103005
> >
> > after I run the following commands:
> >
> > gen double temxxx=(id/1000)
> > gen temyyy=int(temxxx)
> > gen temzzz=temxxx-temyyy
> > gen areaxxx=int(temzzz*1000)
> > list id temxxx temyyy temzzz areaxxx
> >
> > What I got is
> > id         temxxx         temyyy    temzzz  areaxxx
> > 10103005   10103.005      10103     .005      4
> >
> > Is variable areaxxx supposed to be 5? Why did stata give me 4 instead
> of
> > 5? Any clue for this?
> >
> > Thanks.
> >
> > Jian
> 
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