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

Submitter:	Dildar Sk <hodor123456>
Submitted:	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
Fixed Release:	None	Planned Release:	None

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Mon 26 Mar 2018 10:31:20 PM UTC, comment #8: I think so, done.	Mike Miller <mtmiller>
Mon 26 Mar 2018 10:05:50 PM UTC, comment #7: Can we close this as a duplicate of bug #31974?	Rik <rik5>
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>
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>
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>
Sun 25 Mar 2018 02:15:57 PM UTC, comment #2: For infi, 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>
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>

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Depends on the following items

Interpreter fails to create complex numbers with Inf complex parts (bug #31974, Wont Fix)

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Items that depend on this one: None found

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Follow 9 latest changes.

Date	Changed by	Updated Field	Previous Value	Replaced by
2018-03-26	mtmiller	Status	Confirmed	Duplicate
		Open/Closed	Open	Closed
2018-03-26	mtmiller	Dependencies	-	Depends on bugs #31974
2018-03-26	mtmiller	Item Group	Incorrect Result	Matlab Compatibility
2018-03-26	mtmiller	Severity	3 - Normal	2 - Minor
		Priority	5 - Normal	3 - Low
		Status	None	Confirmed
		Summary	angle(0+xi) producing inaccurate result.	Inf*i is not equivalent to complex(0, Inf)
2018-03-25	hodor123456	Carbon-Copy	-	Added -email is unavailable-

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

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

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