Rank: 221 based on 413 downloads (last 30 days) and 19 files submitted
photo

Matt J

E-mail

Personal Profile:

 

Watch this Author's files

 

Files Posted by Matt J View all
Updated   File Tags Downloads
(last 30 days)
Comments Rating
13 Oct 2014 Separable Block-wise Operations Efficiently performs separable operations (e.g., sum, mean,prod, min, max,...) on array sub-blocks Author: Matt J blockproc, mat2cell, blocks, separable, tile 7 0
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 8 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 55 45
  • 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 10 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 52 72
  • 4.61538
4.6 | 13 ratings
Comments and Ratings by Matt J View all
Updated File Comments Rating
03 Dec 2014 Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J

Dear Christophe,

No, changing tolerances won't help. Your problem is ill-posed. Because the ideal triangles only touch at a single point, small perturbations of the input data can make the triangles intersect at multiple points or not at all.

This is why, in the Description section above, I mentioned "It is to be emphasized that A,b must define a solid region". Your intersection point is not solid in R^2, so the inequalities [A1;A2],[b1;b2] are not a legal way of expressing it.

19 Nov 2014 TextZoomable for text that scales as you zoom Text that zooms as you zoom your plot, rather than staying at a fixed font size. Author: Ken Purchase

@David,
I believe the particular error you mention is fixable by changing that line as follows

PostPositionListener = addlistener(hFig,'SizeChanged',...
@(o,e) localPostPositionListener(o,e,imAxes) );

See also the following thread in MATLAB Answers,

<http://www.mathworks.com/matlabcentral/answers/163280-addlistener-syntax-not-recognized-in-r2014b>

However, I'm afraid that even after fixing that, I am finding further problems running TextZoomable in R2014b. In particular, the following lines use undocumented functions findpackage and findclass,

hgp = findpackage('hg');
axesC = findclass(hgp,'axes');

whose behavior has changed somehow.

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

@Bhimavarapu,
The code doesn't generate any plots, but there are other utilities on the FEX that you could use for plotting polyhedra, e.g.,

<http://www.mathworks.com/matlabcentral/fileexchange/9261-plot-2d-3d-region>

As for "not getting the vertices", if you mean you are getting empty output V=[], it means your polyhedron appears empty to the code. Hard to say more without seeing what you're doing.

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

Hi James,
I had a question about how the flags 't' and 'c' are used by sparse matrix arguments. I assume that the flags are there to circumvent explicit transposes and its associated overhead. Yet, it doesn't appear that sparse mtimesx operations make use of them. In the test below, I see basically the same execution speeds in all 3 versions. Is it true that sparse operations can't make use of the flags, and is it deliberate/inevitable? It would be a great benefit to be able to avoid transposing tall sparse matrices because of the high memory consumption that comes with that.

J=sprand(3192027,3225,.0001);

tic;
mtimesx(J,'t',J);
toc

tic;
mtimesx(J.',J);
toc

tic;
J.'*J;
toc

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.

Comments and Ratings on Matt J 's Files View all
Updated File Comment by Comments Rating
03 Dec 2014 Representing Polyhedral Convex Hulls by Vertices or (In)Equalities Express bounded polyhedron via equalities/inequalities or vertices. Author: Matt J Matt J

Dear Christophe,

No, changing tolerances won't help. Your problem is ill-posed. Because the ideal triangles only touch at a single point, small perturbations of the input data can make the triangles intersect at multiple points or not at all.

This is why, in the Description section above, I mentioned "It is to be emphasized that A,b must define a solid region". Your intersection point is not solid in R^2, so the inequalities [A1;A2],[b1;b2] are not a legal way of expressing it.

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

Dear Matt,

tried calculating the intersection between a two triangles touching each other in a point but got following error.

Assume can be solved by setting tolerances correct?

Thanks

Christophe

>> [A1,b1,Aeq1,beq1]=vert2lcon([2,0;0,2;0,0]);
>> [A2,b2,Aeq2,beq2]=vert2lcon([1,1;2,1;1,2]);
>> V = lcon2vert([A1;A2],[b1;b2],[],[])
Something's wrong. We should have found a recession vector (bb<0).

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

@Bhimavarapu,
The code doesn't generate any plots, but there are other utilities on the FEX that you could use for plotting polyhedra, e.g.,

<http://www.mathworks.com/matlabcentral/fileexchange/9261-plot-2d-3d-region>

As for "not getting the vertices", if you mean you are getting empty output V=[], it means your polyhedron appears empty to the code. Hard to say more without seeing what you're doing.

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

Dear Sir,
Even I am giving A,b I am not getting the vertices and also not getting the plot

06 Nov 2014 Absolute Orientation - Horn's method Solves weighted absolute orientation problem using Horn's quaternion-based method. Author: Matt J ZZZZZ

Contact us