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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Hi<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>This occurs in most programming languages
due to the way floating point arithmetic is performed. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If I try it in Python I get:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>>>> 123123123123123123123.0 -
123123123123123123121.0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>0.0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Take out the decimal place and you get:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>>>> 123123123123123123123 -
123123123123123123121<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>2<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Try the following in Erlang:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>10.1-0.1-10 = 0.00000e+0<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>However:<o:p></o:p></span></font></p>
<p class=MsoNormal><a name="OLE_LINK2"></a><a name="OLE_LINK1"><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>10.1-10-0.1 </span></font></a><font size=2 color=navy face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:navy'>= -3.60822e-16<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>It’s not a bug, it’s a limitation<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Regards,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Trevor<o:p></o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> erlang-questions-bounces@erlang.org
[mailto:erlang-questions-bounces@erlang.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Gurgen Tumanian<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, 08 May 2008 10:42
AM<br>
<b><span style='font-weight:bold'>To:</span></b> erlang-questions@erlang.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> [erlang-questions]
Strange arithmetic behaviour</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Dear all.<br>
<br>
There is some kind of strange behaviour that i have noticed when dealing with
big float values.<br>
For example:<br>
<br>
123123123123123123123.0 - 123123123123123123121.0 is 0.00000e+0
when i expect 2.0 or something like that in e notation.<br>
I found this kind of errors with round() and trunc(). for example: <br>
trunc(1233333333333333123333333333.12311111111) is
1233333333333333065680814080.<br>
or<br>
round(1233333333333333123333333333.12311111111) is
1233333333333333065680814080.<br>
<br>
furthermore <br>
1233333333333333123333333333.12311111111 =
123333333333333312367575676573.92311111111 matches<br>
<br>
<br>
I have tested this on R11-B5 and on R12-B1<br>
<br>
Is this a big nasty bug, or am i missing something?<br>
<br>
Regards<br>
Gurgen Tumanyan<br>
Smart Tech<br>
<br>
<br>
<o:p></o:p></span></font></p>
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