bugGNU Octave - Bugs: bug #53462, Inf*i is not equivalent to...

 
 

bug #53462: Inf*i is not equivalent to complex(0, Inf)

Submitted by:  Dildar Sk <hodor123456>
Submitted on:  Sun 25 Mar 2018 01:55:31 PM UTC  
 
Category:  Octave Function Severity:  2 - Minor
Priority:  3 - Low Item Group:  Matlab Compatibility
Status:  Duplicate Assigned to:  None
Originator Name:  Dildar Sk Open/Closed:  Closed
Release:  dev Operating System:  GNU/Linux

Add a New Comment (Rich Markup)
   

You are not logged in

Please log in, so followups can be emailed to you.

 

( Jump to the original submission)

Mon 26 Mar 2018 10:31:20 PM UTC, comment #8: 

I think so, done.

Mike Miller <mtmiller>
Project Administrator
Mon 26 Mar 2018 10:05:50 PM UTC, comment #7: 

Can we close this as a duplicate of bug #31974?

Rik <rik5>
Project Administrator
Mon 26 Mar 2018 07:01:02 PM UTC, comment #6: 

And this seems to be covered pretty thoroughly by bug #31974.

Mike Miller <mtmiller>
Project Administrator
Mon 26 Mar 2018 06:58:57 PM UTC, comment #5: 

I've updated the summary and metadata to reflect the remaining issue here. In Matlab, Inf*i evaluates to complex(0, Inf).

Mike Miller <mtmiller>
Project Administrator
Sun 25 Mar 2018 03:31:34 PM UTC, comment #4: 

"What happens for you if you do",

angle (complex (0, Inf))
angle (complex (NaN, Inf))
angle (complex (Inf, NaN))
angle (complex (NaN, NaN))
angle (complex (Inf, Inf))

Yes,the results are same in MATLAB and Octave.

Dildar Sk <hodor123456>
Sun 25 Mar 2018 02:17:19 PM UTC, comment #3: 

That should have been

For

inf * i

Octave computes...

John W. Eaton <jwe>
Project Administrator
Sun 25 Mar 2018 02:15:57 PM UTC, comment #2: 

For inf*i, Octave computes inf * complex (0, 1), which produces complex (NaN, Inf), so I think angle is doing the right thing to return NaN for that value.

What happens for you if you do

angle (complex (0, Inf))
angle (complex (NaN, Inf))
angle (complex (Inf, NaN))
angle (complex (NaN, NaN))
angle (complex (Inf, Inf))

in both Octave and Matlab?

If these all agree, then I think the actual "problem" is that Octave doesn't have a special case for Inf * i.  The real issue here is that Octave (and Matlab) don't have pure imaginary numbers.  So given that, the question is what (if any) special cases should be handled for operations when the real part of a complex number is zero.  We've been over this issue a number of times before, and it's not clear to me what the correct thing is.

John W. Eaton <jwe>
Project Administrator
Sun 25 Mar 2018 02:01:05 PM UTC, comment #1: 

I am really sorry, there was a i variable present there, so the following report isn't valid.But,
angle(inf*i) producing different result in MATLAB and Octave.
MATLAB giving pi/2 where Octave giving NaN.

Dildar Sk <hodor123456>
Sun 25 Mar 2018 01:55:31 PM UTC, original submission:  

In MATLAB,

>> angle(i)

ans =

    1.5708

>> angle(10i)

ans =

    1.5708

In Octave,

>> angle(i)
ans = 0
>> angle(10i)
ans =  1.5708

angle(x+iy) is equal to,atan(y/x),
so,angle(0+iy)=atan(y/0)=atan(inf)=pi/2.
Definite the answer should be like MATLAB 1.5708.

Dildar Sk <hodor123456>

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:
   
   
Comment:
   

No files currently attached

 

Digest:
   bug dependencies.

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by rik5 (Posted a comment)
  • -email is unavailable- added by mtmiller (Posted a comment)
  • -email is unavailable- added by jwe (Posted a comment)
  • -email is unavailable- added by hodor123456 (Submitted the item)
  • -email is unavailable- added by hodor123456
  •  

    Do you think this task is very important?
    If so, you can add your encouragement to it.
    This task has 0 encouragements so far.

    Only project members can vote.

     

     

     

    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2018-03-26 mtmiller StatusConfirmed => Duplicate
        Open/ClosedOpen => Closed
    2018-03-26 mtmiller Dependencies- => Depends on bugs #31974
    2018-03-26 mtmiller Item GroupIncorrect Result => Matlab Compatibility
    2018-03-26 mtmiller Severity3 - Normal => 2 - Minor
        Priority5 - Normal => 3 - Low
        StatusNone => Confirmed
        Summaryangle(0+xi) producing inaccurate result. => Inf*i is not equivalent to complex(0, Inf)
    2018-03-25 hodor123456 Carbon-Copy- => Added dildarsk101010@gmail.com

    Back to the top


    Powered by Savane 3.5