floating-point number - hardware or lisp dependent?

My guess is that the numbers are reading correctly, but not being correctly
rounded when printed.  Even the same Lisp might be using different
numerical libraries on different platforms.

What is rationalize(X) for the numbers in question?  That would show the
exact internal representation.

             -s


On Thu, Apr 4, 2013 at 3:09 PM, Volker van Nek <volkervannek at gmail.com>wrote:

> build_info();
>
> gives the information you want. Below there are some examples.
>
> If I am not mistaken Maxima on Windows is compiled with GCL, Ubuntu uses a
> SBCL-compiled version and I believe MAC uses SBCL too.
>
> Surprisingly CMUCL doesn't like 5e-324, 4e-324, 3e-324.
>
> Volker
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 11:04:01"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "GNU Common Lisp (GCL)"
> Lisp implementation version: "GCL 2.6.7"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
> (%o2) [1.23456789E+7, 1.2345678912345672E+8, 5.0d-324, 4.0d-324, 3.0d-324]
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 13:00:53"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "SBCL"
> Lisp implementation version: "1.0.57.0.debian"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
> (%o2) [1.2345678900000001e+7, 1.2345678912345673e+8,
> 4.94065645841247e-324,
>                                                                       0.0,
> 0.0]
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 13:10:21"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "ECL"
> Lisp implementation version: "11.1.1"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
> (%o2) [1.23456789e+7, 1.2345678912345671e+8, 4.940656458412466e-324,
>                                 4.940656458412466e-324,
> 4.940656458412466e-324]
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 13:04:34"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "Clozure Common Lisp"
> Lisp implementation version: "Version 1.8-r15286M  (LinuxX8632)"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
> (%o2) [1.23456789E+7, 1.2345678912345672E+8, 5.0E-324, 5.0E-324, 5.0E-324]
>
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 12:58:55"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "CLISP"
> Lisp implementation version: "2.49 (2010-07-07) (built 3539672548) (memory
> 3573975538)"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
> (%o2)        [1.23456789E+7, 1.2345678912345671E+8, 0.0, 0.0, 0.0]
>
>
> (%i1) build_info();
> (%o1)
> Maxima version: "5.30.0"
> Maxima build date: "2013-04-03 12:59:52"
> Host type: "i686-pc-linux-gnu"
> Lisp implementation type: "CMU Common Lisp"
> Lisp implementation version: "Debian build debian/20c-2-1-g957a42a-dirty
> (20C Unicode)"
> (%i2) [12345678.9, 123456789.12345671, 5e-324, 4e-324, 3e-324];
>
> Maxima encountered a Lisp error:
>
>  Reader error at 8 on #<String-Input Stream>:
> Floating-point number not representable
>
> ...
>
>
>
>
> 2013/4/4 Jorge Calvo <Jorge.Calvo at avemaria.edu>
>
>> Hello there:
>>
>> A recent comment by Volker van Nek <volkervannek at gmail.com<mailto:
>> volkervannek at gmail.com>> on the "scientific notation - truncation"
>> thread (Message-ID: <
>> CAKFbC62j2QbOcUJfrt22zhjAsSVx90jBmtOqPzVzhhLSi4adCw at mail.gmail.com
>> <mailto:
>> CAKFbC62j2QbOcUJfrt22zhjAsSVx90jBmtOqPzVzhhLSi4adCw at mail.gmail.com>>)
>> reminded me of a curious issue that I discovered a few months ago while
>> teaching a course in "scientific programming."  The students in the class
>> run Maxima on a variety of platforms (mostly Mac and PC) and as a result,
>> from time to time there are some slight differences in the answers they
>> get.  For example, suppose that we enter:
>>
>> (%i1) 12345678.9;
>> (%i2) 123456789.12345671;
>> (%i3) 5e-324;
>> (%i4) 4e-324;
>> (%i5) 3e-324;
>>
>> Running on a Mac, I get:
>>
>> (%o1) 1.2345678900000001*10^7
>> (%o2) 1.2345678912345673*10^8
>> (%o3) 4.94065645841247*10^-324
>> (%o4) 0.0
>> (%o5) 0.0
>>
>> But on a Windows machine, I get:
>>
>> (%o1) 1.23456789*10^7
>> (%o2) 1.2345678912345672*10^8
>> (%o3) 4.9406564584124654*10^-324
>> (%o4) 4.9406564584124654*10^-324
>> (%o5) 0.0
>>
>> I initially assumed the difference was in the hardware implementation of
>> floats, but Volker's comment makes me wonder whether the difference might
>> be the underlying Lisps.  Can anyone shed some light on this?  Is there a
>> way that a newbie like me can check what version of Lisp is lying under
>> their Maxima?
>>
>> Thanks for your assistance,
>>
>> Jorge
>> --
>> Dr. Jorge Alberto Calvo
>> Associate Professor of Mathematics
>> Department of Mathematics and Physics
>> Ave Maria University
>>
>> Phone: (239) 280-1608
>> Email: jorge.calvo at avemaria.edu<mailto:jorge.calvo at avemaria.edu>
>> Web: http://sites.google.com/site/jorgealbertocalvo
>>
>>
>>
>>
>> _______________________________________________
>> Maxima mailing list
>> Maxima at math.utexas.edu
>> http://www.math.utexas.edu/mailman/listinfo/maxima
>>
>
>
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