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From: johnk%suned@cs.yale.edu (john james kuszewski)
Newsgroups: comp.lang.fortran
Subject: conversion to double precision
Summary: how do I convert real to double properly?
Keywords: double precision single precision convert type
Message-ID: <25734@cs.yale.edu>
Date: 4 Aug 90 22:23:38 GMT
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Originator: johnk@suned.CS.Yale.Edu

I'm having some difficulty converting REAL variables to DOUBLE
PRECISION.  All the manuals I've seen say that the REAL value 
is put in the most significant portion of the D.P. variable and
the least significant portion is zeroed out.  However, when I 
execute

REAL X
X = 1.23E0
TYPE *, 'SINGLE', X
TYPE *, 'DOUBLE', DBLE(X)
     
I get

SINGLE   1.230000
DOUBLE   1.23000001907349

If I'm reading the manual properly, those least-significant D.P.
digits should be zeros.  What's the problem here?  If this is what 
FORTRAN is supposed to do, how can I force it to zero out those
least-significant digits?  Sorry if this is a stupid question, 
but it's driving me nuts.  

Thanks.

John Kuszewski
kuszewsk@euler.biology.yale.edu


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