bugGNU Octave - Bugs: bug #65091, [octave forge] (nurbs) nrbderiv...

 
 

bug #65091: [octave forge] (nurbs) nrbderiv outputs nurbs with zero weight.

Submitter:  Liang Tang <lt1234>
Submitted:  Thu 28 Dec 2023 10:40:19 PM UTC
   
 
Category:  Octave Forge Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  lt1234 Open/Closed:  * Open
Release:  * 8.2.0 Operating System:  * Microsoft Windows
Fixed Release:  None Planned Release:  None
* Mandatory Fields

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Thu 28 Dec 2023 10:40:19 PM UTC, original submission:  

nrbderiv resets the nurbs weight to zero in build-in bspderiv. nrbkntplot would not plot a nurbs with zero weights. Please see the attached ofig.  Thanks. 

pkg load nurbs
Q=[0, 0; 3,4;-1,4;-4,0;-4,-3]
p=3; % cubic
%
P=[0        0; ...
   7.3170   3.6868; ...
  -2.9581   6.6783; ...
  -4.4950  -0.6737; ...
  -4.0000  -3.0000];
U=[0        0        0        0   0.5490   1.0000   1.0000   1.0000   1.0000];
nurbs   = nrbmak(cp=P',knots=U);
nurbs_d = nrbderiv (nurbs);nurbs_d.coefs  % zero weight

figure('name', 'nrbderiv weight=0');
 
subplot(1,2,1); % no plot
nrbkntplot(nurbs_d);  

subplot(1,2,2); % plot
nurbs_d.coefs(4,:)=[1 1 1 1];
nrbkntplot(nurbs_d);

Liang Tang <lt1234>

 

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Attached Files
file #55486:  nrbkntplot.ofig added by lt1234 (91KiB - application/octet-stream)

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2023-12-28 lt1234 Attached File- Added nrbkntplot.ofig, #55486

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