[Octave-bug-tracker] [bug #64655] [Octave Forge] (Symbolic) A problem with evaluating symbolic expression

[Ahmed Salah Hammad Ahmed]

URL:
  <https://savannah.gnu.org/bugs/?64655>

                 Summary: [Octave Forge] (Symbolic) A problem with evaluating
symbolic expression
                   Group: GNU Octave
               Submitter: asalahhammad
               Submitted: Mon 11 Sep 2023 03:20:05 PM UTC
                Category: Octave Forge Package
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
                 Release: other
         Discussion Lock: Any
        Operating System: GNU/Linux
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Mon 11 Sep 2023 03:20:05 PM UTC By: Ahmed Salah Hammad Ahmed
<asalahhammad>
Whenever there's an expression that looks exactly like this and with such
large numbers as coefficients:


syms x y z
exp = 1.435647686e28 * (1e-19*x + 1e-22*y + z*1e-15)
        [Output]:
                  9223372036854775807⋅z
          x + y +
─────────────────────
                     1000000000000000
vpa(ans)
        [Output]:
        ans = (sym) x + y + 9223.37203686⋅z


which is obviously wrong.. and the problem persists whenever an expression is
evaluated, for example:

f = @(x,y,z) 1.435647686e28 * (1e-19*x + 1e-22*y + z*1e-15)
        [Output]:
        f =
        @(x, y, z) 1.435647686e28 * (1e-19 * x + 1e-22 * y + z * 1e-15)
syms x y z
f(x,y,z)
        [Output]:
                  9223372036854775807⋅z
          x + y +
─────────────────────
                     1000000000000000



And even when sending the whole expression to the built in function 'eval' and
started debugging a little, the expression keeps ok until it is evaluated at
the function fh, as appearing in the screenshot attached

And.., the same code works on matlab well..

I tried the same thing using octave v:7.1.1 and v:9.0.0 on a PC with Linux
Ubuntu 20.04






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File Attachments:


-------------------------------------------------------
Date: Mon 11 Sep 2023 03:20:05 PM UTC  Name:
Screenshot@from@2023-09-11@18-00-42.png  Size: 95KiB   By: asalahhammad

<http://savannah.gnu.org/bugs/download.php?file_id=55128>

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