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Re: st: Mata buffered read 64-bit integer (8 byte/int64), how?


From   Sergiy Radyakin <serjradyakin@gmail.com>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Mata buffered read 64-bit integer (8 byte/int64), how?
Date   Thu, 13 Jun 2013 16:55:55 -0400

Thank you, Stas,
this is what I am doing now. Storage in a struct (or in my case simply
in two real variables) is not a problem. The problem starts when you
need one (LARGE) value, then x=x1*2^32+x2 becomes already lossy, since
(as the manual says) : "Doubles can store up to 9,007,199,254,740,991
exactly". Not that I would expect anyone to have files that big :)
but formally I want to be on the safe side and I didn't expect a
problem having 64-bit integers in (at least) 64-bit Stata.

Sergiy

On Thu, Jun 13, 2013 at 4:48 PM, Stas Kolenikov <skolenik@gmail.com> wrote:
> You can probably define the -struct-ure that could store such strings,
> and convert them into numbers for arithmetic operations. Bill Gould
> may have had an article on this in Stata Journal -- the generic use of
> structures is described in
> http://www.stata-journal.com/sjpdf.html?articlenum=pr0035. Coding
> matrix multiplication with these elements will quickly become an
> overkill :-\.
>
> -- Stas Kolenikov, PhD, PStat (SSC)
> -- Senior Survey Statistician, Abt SRBI
> -- Opinions stated in this email are mine only, and do not reflect the
> position of my employer
> -- http://stas.kolenikov.name
>
>
>
> On Thu, Jun 13, 2013 at 3:12 PM, Sergiy Radyakin <serjradyakin@gmail.com> wrote:
>> I read a 32-bit integer value from a buffered file with d=fbufget(C,fh,"%4bu").
>>
>> How do I read a 64-bit integer from the same file when Mata does not
>> support format "%8bu"? And what can be the type of the LHS (type of
>> variable d above) to accommodate the result of the read without the
>> loss of information (double is not good, not sure about quad
>> precision).
>>
>> I can read it as 8-bytes string, or 8 individual bytes, but I also
>> need to work with the result as a value in Mata. So looking for a
>> convenient solution.
>>
>> Thank you,
>>      Sergiy
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