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Re: st: a question on function int


From   Chris Kopp <kopp@soz.unibe.ch>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: a question on function int
Date   Thu, 20 Oct 2005 01:52:57 +0200

Dear Zhang,

-help datatypes- explains that Stata saves numbers in binary format. Numbers less than 1, such as 0.005 in your case, may not have a perfect binary representation. So if you type -list if temzzz==0.005-, no cases will be displayed. But if you type -list if temzzz<0.005-, your case will be listed. This explains what happens next: for Stata, the value of temzzz is smaller than 0.005, which yields your result. Further references can be foung in -help datatypes- as well, but I work away from my manuals at the moment, so I can't help you there. I know other users will be able to do much better, but it's a first pointer.

Have a nice day, Chris

On Oct 19, 2005, at 22:30, Jian Zhang wrote:


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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