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st: RE: reading a value from a file into a scalar


To   statalist@hsphsun2.harvard.edu
Subject   st: RE: reading a value from a file into a scalar
From   Finne Håkon <Hakon.Finne@sintef.no>
Date   Thu, 6 Jun 2002 17:55:45 +0200
Reply-to   statalist@hsphsun2.harvard.edu
Sender   owner-statalist@hsphsun2.harvard.edu

Here is an unfinished idea:
Unless you are using Stata for Macintosh, -environment name- will return the
contents of the operating system's environment variable so named. If you
could write the output number of your Maple operation (as a string, I think
is better) to the operating system environment, then that's a place where
Stata could pick it up. For example, under Windows, the Stata command -!set
/p maple=<c:\maple.txt- would make Windows read its maple environment
variable from the contents of the file c:\maple.txt . Unfortunately,
however, this particular env.var. is only available directly within the
shell opened by ! , which closes before you go back to Stata ; so you would
have find a way to set a more 'permanent' environment variable either from
within Stata or from Maple or from a batch file that contains the maple
command and the inv.vir. command and is invoked from Stata. This might be
easier under Unix - ??

I hope this helps.

Håkon

Håkon Finne
http://www.sintef.no

> -----Original Message-----
> From: Chris Wallace [mailto:Chris.Wallace@lshtm.ac.uk]
> Sent: 6. juni 2002 16:59
> To: statalist@hsphsun2.harvard.edu
> Subject: st: reading a value from a file into a scalar
> 
> 
> Dear statalisters,
> 
> I am using -ml- to maximize a multiple equation model.  One of the
> steps in calculating the likelihood involves finding a particular
> solution to a quartic.
> 
> I have written a function to do this in maple, and now want 
> to use this
> from within stata.  I am hoping to do this by calling maple from stata
> 
> . shell maple < maple_command_file
> 
> and writing the result from maple into a file, then reading that into
> stata as I don't believe stata will accept a return value from shell. 
> Can I assign the contents of a file (which I know will be a single
> number) to a scalar?  How?
> 
> I'd rather not mess about with reading the single value using 
> -infile-,
> bc then I'd have to -preserve-/-restore- my rather large dataset each
> time.
> 
> I know I could also try using -bisect- from within Stata, but suspect
> maple would be significantly faster if only I could get the 2 programs
> to communicate nicely.  My worry with using maple is the errors that
> might result from forcing stata and maple to read/write 
> representations
> of numbers to files.
> 
> Thanks for any suggestions, Chris.
> 
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