Rank: 174 based on 409 downloads (last 30 days) and 18 files submitted
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Matt J

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Professional Interests:
medical image processing, optimization algorithms

 

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Files Posted by Matt J View all
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(last 30 days)
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07 Mar 2014 Clean anonymous functions of excess memory Tries to purge an anonymous function of non-essential workspace variables Author: Matt J anonymous function, memory, parfor 7 0
06 Jan 2014 Screenshot Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J vert2con, polyhedron, polytope, vertices, convex hull, convhull 48 41
  • 5.0
5.0 | 12 ratings
11 Dec 2013 FUNC2MAT: Convert linear function to matrix A utility to obtain the matrix representing a given linear function Author: Matt J linear function, matrix form, gradient, transpose, optimization toolbox, parameter estimation 5 0
13 Mar 2013 N-dimensional sparse arrays Creates an N-dimensional sparse array object, for arbitrary N. Author: Matt J sparse, ndimensional, multidimensional, oop, reshape, sparse array 35 72
  • 4.58333
4.6 | 12 ratings
15 Feb 2012 Split nD-array into equal sized cells Splits an array of any dimension into cell array of equal sized chunks. Author: Matt J blockproc, mat2cell, block, blocks, 8x8, dct 26 0
Comments and Ratings by Matt J View all
Updated File Comments Rating
12 Aug 2014 3D Rotation about Shifted Axis Computes/applies rotation about arbitrary 3D line. Author: Matt J

@Michael
Not sure I understand your question. You can rototranslate one or more 3D column vectors using SYNTAX 3 of the routine.

31 Jul 2014 Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J

Cong,

Points on the boundary of the polytope are expected to violate the inequalities by small amounts due to finite precision arithmetic. When I compute the violations for your A,b data with the code below, I find that they are indeed very small O(1e-13),

>> V=lcon2vert(A,b);
>> slacks=bsxfun(@minus, b,A*V');
>> violations = slacks(slacks<0)

violations =

1.0e-13 *

-0.1066
-0.0355
-0.5684
-0.0711
-0.0355
-0.0355
-0.5684
-0.0355
-0.2842
-0.5684
-0.1066
-0.2487
-0.3375

19 Jul 2014 uitable UITABLE creates a 2D graphic uitable as an alternative to MATLAB 7's UITABLE (MATLAB 6.5, no-JAVA mo Author: Todd Pataky

19 Jun 2014 uitable UITABLE creates a 2D graphic uitable as an alternative to MATLAB 7's UITABLE (MATLAB 6.5, no-JAVA mo Author: Todd Pataky

It's almost exactly what I need, but with some unfortunate flaws. I'd be willing to raise my rating if the table and its window were made resizable. Also, it is strange that an error message

Error using guitable>callback_close (line 1347)
Use the "OK" or "cancel" button to exit modal mode.

is given when trying to close the table window. Seems to me that the close button should simply be interpreted as "cancel".

18 Jun 2014 MTIMESX - Fast Matrix Multiply with Multi-Dimensional Support Beats MATLAB 300% - 400% in some cases ... really! Author: James Tursa

Thanks, James. This thread describes where the information has moved to

http://www.mathworks.com/matlabcentral/answers/67521#answer_138814

I can post those xml files somewhere, if you like. However, is there no way to get mtimesx to compile simply with the "mex" command, maybe with a small sacrifice in performance?

Comments and Ratings on Matt J's Files View all
Updated File Comment by Comments Rating
12 Aug 2014 3D Rotation about Shifted Axis Computes/applies rotation about arbitrary 3D line. Author: Matt J Matt J

@Michael
Not sure I understand your question. You can rototranslate one or more 3D column vectors using SYNTAX 3 of the routine.

12 Aug 2014 3D Rotation about Shifted Axis Computes/applies rotation about arbitrary 3D line. Author: Matt J Michael

How could you modify this code to rotate/translate a 3D velocity vector instead of just a coordinate frame?

31 Jul 2014 Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J Matt J

Cong,

Points on the boundary of the polytope are expected to violate the inequalities by small amounts due to finite precision arithmetic. When I compute the violations for your A,b data with the code below, I find that they are indeed very small O(1e-13),

>> V=lcon2vert(A,b);
>> slacks=bsxfun(@minus, b,A*V');
>> violations = slacks(slacks<0)

violations =

1.0e-13 *

-0.1066
-0.0355
-0.5684
-0.0711
-0.0355
-0.0355
-0.5684
-0.0355
-0.2842
-0.5684
-0.1066
-0.2487
-0.3375

31 Jul 2014 Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J Cong

I just did a test about your program, and I found that an extreme vertex that obtained does not satisfy all inequalities. Note that I just test inequalities case (3D):
A=
-32.7680000000000 17.6400000000000 -3.20000000000000
-3.37500000000000 6.25000000000000 -1.50000000000000
17.5760000000000 2.56000000000000 2.60000000000000
79.5070000000000 10.8900000000000 4.30000000000000
32.7680000000000 -17.6400000000000 3.20000000000000
3.37500000000000 -6.25000000000000 1.50000000000000
-17.5760000000000 -2.56000000000000 -2.60000000000000
-79.5070000000000 -10.8900000000000 -4.30000000000000
b=
5
18
68
244
2
-11
-61
-219
One of the extreme vertices: [1.5530 4.9322 9.7233]
In order to test if this three values satisfy all inequalities, I multiply A by [1.5530 4.9322 9.7233]' to compare the new set of b values with the previous b values, and I found not all of new b values less than the original b values, which means they are not satisfied.

23 Jun 2014 Absolute Orientation - Horn's method Solves weighted absolute orientation problem using Horn's quaternion-based method. Author: Matt J Bar-Yehuda, Zohar

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