bugGNU Octave - Bugs: bug #35680, mod does not warn when losing...


bug #35680: mod does not warn when losing precision

Submitted by:  None
Submitted on:  Thu 01 Mar 2012 04:21:20 PM UTC  
Category:  Interpreter Severity:  2 - Minor
Priority:  3 - Low Item Group:  Incorrect Result
Status:  Wont Fix Assigned to:  None
Originator Name:  Originator Email:  -email is unavailable-
Open/Closed:  Closed Release:  3.2.4
Operating System:  Any

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Tue 22 Dec 2015 04:37:13 PM UTC, comment #2: 

Closing as won't fix, Octave is working as expected with numerical values with limited precision.

The symbolic package is now fully functional, so if you want arbitrary precision the vpa class takes care of this type of problem:

>> y = 98 - mod (60392010507000000, 97)
y =  50
>> y = 98 - mod (vpa (60392010507000000), 97)
y = (sym) 47.000000000000000000000000000000

Mike Miller <mtmiller>
Project Administrator
Thu 01 Mar 2012 04:32:14 PM UTC, comment #1: 

This essentially the same as bug #32924. I'm marking it as a duplicate.

I'm also lowering the priority. Octave is not a CAS and integers have limited precision.

Jordi GutiƩrrez Hermoso <jordigh>
Project Administrator
Thu 01 Mar 2012 04:21:20 PM UTC, original submission:  

I've found an error when computing mod97.

FORMULA: 98 - mod(data, 97)

EXAMPLE: 98 - mod(60392010507000000, 97)

But it should be 47, not 50! overflow?

I think the mod() formula should launch a warning or something else to indicate problem.



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    Follow 10 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-11-20 mtmiller Dependencies- => patch #9875 is dependent
    2015-12-22 mtmiller StatusDuplicate => Wont Fix
        Open/ClosedOpen => Closed
    2012-03-01 rik5 Carbon-CopyRemoved 72865 => -
    2012-03-01 rik5 Priority5 - Normal => 3 - Low
    2012-03-01 jordigh Operating SystemMicrosoft Windows => Any
    2012-03-01 jordigh Severity3 - Normal => 2 - Minor
        StatusNone => Duplicate
        Summarymod97 incorrect result => mod does not warn when losing precision
    2012-03-01 jordigh Dependencies- => Depends on bugs #32924

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