Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!snorkelwacker!bloom-beacon!eru!luth!sunic!tut!ra!uwasa.fi!ts
From: ts@uwasa.fi (Timo Salmi LASK)
Newsgroups: comp.lang.pascal
Subject: Re: Problem in Turbo Pascal 4.0
Keywords: Nonterminating Repeat loop, real, representation
Message-ID: <1990Jan4.081234.7882@uwasa.fi>
Date: 4 Jan 90 08:12:34 GMT
References: <4658@ur-cc.UUCP> <4660@ur-cc.UUCP> <803@tuewsd.lso.win.tue.nl>
Organization: University of Vaasa
Lines: 31

In article <803@tuewsd.lso.win.tue.nl> wsinkees@lso.win.tue.nl (Kees Huizing) writes:
>lowj_ltd@uhura.cc.rochester.edu (John Alan Low) writes:
>
>>In article <4658@ur-cc.UUCP> I wrote: 
>>>I am having a problem with Turbo Pascal 4.0. The repeat loop in the following
>>>loop never terminates. 
>>>Program Foo;
>>>var  x : real;
>>>Begin
>>>x := 0.10;
>>>     Repeat
>>>     x := x + 0.01;
>>>     Until x = 0.30;
>>>End.
>
>>     Thanks to everybody who emailed me on this. I forgot that 0.01 is a
>>     repeating decimal in binary. I never will again.

One (similar) solution as has been pointed out by many netters is
using
  function Equal (a, b : real) : boolean;
  begin
    if abs(a-b) < 1.0E-5 then equal := true else equal := false;
  end;
  .
  Until Equal (x, 0.30);

...................................................................
Prof. Timo Salmi                                (Site 128.214.12.3)
School of Business Studies, University of Vaasa, SF-65101, Finland
Internet: ts@chyde.uwasa.fi Funet: vakk::salmi Bitnet: salmi@finfun