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Re: st: Precision


From   Sergio Correia <sergio.correia@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Precision
Date   Fri, 11 Nov 2005 09:24:39 -0500

That's a tough one.

First, I tried using
gen double y = real(x)

(Variables with type -double- have, well, double precision)

However, as the following example can show, this is not enough to
maintain ALL the precision.

1) make the data
input str20 x
348080.2688552010
end

2)
gen a=real(x)
gen double b=real(x)
destring x, gen(c)
browse

3) Alternative (a) is pretty bad.
(b) and (c) give 3.4808026885520e+05, which is pretty close.

If that is not enough, I can't help.

By the way, you can try importing the data specifying it as -double-.
The exact way to do this depends on whether you use -insheet-,
-infile-, etc. Search the help of the command you used for a -double-
option or something like that.

Sergio


On 11/11/05, Ronnie Babigumira <ronnie.babigumira@umb.no> wrote:
> Dear all
> I have scanned some of the previous posts on this subject but I am not
> making any headway.
>
> I have text file with two variables whose contents are 16 digit numbers
> of the form
>
> x
> 348080.2688552010
>
> I would like to import the data into stata whilst maintainig the
> precision. Here is what I have done. I import the variables as strings
> and that works. However, the next challenge is that they need to be used
> as numeric variables (this is the hair loss part). I have tried
>
> gen y = real(x)
> destring x, gen(y)
>
> Both dont have an option to specify the format. Trying to format the
> generated variables also wont help since format y %9.11f  gives me the
> dreaded red lines and blue lines
>
> invalid %format
> r(120);
>
> So my question is how can I change x from string to numeric whilst
> maintaining the precision. Or even better, how best can I import this
> into stata as a numeric variable without loss of precision.
>
> Ronnie
> *
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>

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