Here's something weird and probably related:
. clear
. set obs 1
obs was 0, now 1
. gen ID = 21557127
. display ID
21557128
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jian Zhang
Sent: Friday, March 31, 2006 5:33 PM
To: [email protected]
Subject: st: a question about number precision
Dear Stata Users,
I have a problem about number precision. I cann't figure out what it
happened. Hope that you can help me out. Thanks.
Here is the data:
ID
21557127
then i run the following do file trying to extract the last three digits
from the ID:
gen double temxxx=(ID/1000)
gen temyyy=int(temxxx)
gen temzzz=temxxx-temyyy
gen areaxxx=(temzzz*1000)
drop temxxx temyyy temzzz
the generated data looks like the following:
ID areaxxx
21557127 127
However, when I typed: list if areaxxx==127, stata in fact listed
nothing!
First I thought it may be because areaxxx is a floating-point variable,
so I type: list if areaxxx=float(127). However, Stata listed nothing
again.
Then I tried changing the do file a little bit:
gen double temxxx=(ID/1000)
gen temyyy=int(temxxx)
gen temzzz=temxxx-temyyy
gen areaxxx=float(temzzz*1000)
drop temxxx temyyy temzzz
after running the do file, the data is exactly same:
ID areaxxx
21557127 127
However, when I typed list if areaxxx==127, stata listed nothing again!
I am really confused and could not figure out why stata treated the
number this way. Hope that you can help me out. Thanks.
Jian Zhang
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