bugGNU Octave - Bugs: bug #57614, quadgk integrates complex paths in...

 
 

bug #57614: quadgk integrates complex paths in reverse direction to specified "Waypoints"

Submitter:  Rik <rik5>
Submitted:  Thu 16 Jan 2020 11:31:39 PM UTC
   
 
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Thu 16 Jan 2020 11:55:17 PM UTC, comment #1: 

Someone had mistakenly used the Hermitian transpose (') instead of the physical transpose (.') so complex Waypoints were being conjugated and the integral was reversing.

Fixed in this cset: https://hg.savannah.gnu.org/hgweb/octave/rev/14efec874546.

Rik <rik5>
Group administrator
Thu 16 Jan 2020 11:31:39 PM UTC, original submission:  

quadgk performs path integrals in reverse which results in a change of sign for the output.

Sample integration


fun = @(z) exp(z)./z;
C = [1+i -1+i -1-i 1-i];
q2 = integral(fun,1,1,'Waypoints',C)
q2 = -9.8879e-17 - 6.2832e+00i


Exact result is


2*pi*i



Rik <rik5>
Group administrator

 

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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2020-01-16 rik5 StatusConfirmed Fixed
        Open/ClosedOpen Closed

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