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From:	=?iso-8859-15?Q?Rafael_Garc=EDa?= <rafael AT geninfor DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	double with only 13 digit precision?
Date:	Thu, 30 Oct 2003 14:07:52 +0100
Organization:	Telefonica Data Espagna
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I thought type double had at least 15 decimal digits of precision, but I 
have found I can get a result with only 13 precise digits. Can anyone 
please explain that result?
Thanks


#include <stdio.h>

int main() {
   double a=4777.91;
   double b=4782.98;
   double c=a-b; printf("%.18g-%.18g=%.18g\n",a,b,c);
   // show count of significant digits:
   printf("1234 56789abcdefgXX 1234 56789abcdefgXX  1 23456789abcXXXXXX\n") 
;
   printf("                ^OK                 ^OK               ^Why??\n") 
;
   printf(" 16 digit precision  16 digit precision   13 digit precision\n") 
;

   return 0;
   }

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