# Matt J

Professional Interests: medical image processing, optimization algorithms

PLEASE NOTE: I do not read email sent through my author page. Please post questions about FEX submissions in their respective Comments section.

**Statistics**

RANK**6**

of 246.638

REPUTATION**21.796**

CONTRIBUTIONS

**200** Questions

**8.543** Answers

ANSWER ACCEPTANCE **
75.0%
**

VOTES RECEIVED**2.889**

RANK**254** of 17.206

REPUTATION**5.303**

AVERAGE RATING**4.90**

CONTRIBUTIONS**33** Files

DOWNLOADS **359**

ALL TIME DOWNLOADS**44286**

CONTRIBUTIONS**0 Posts**

CONTRIBUTIONS**0** Public Channels

AVERAGE RATING

CONTRIBUTIONS**0** Highlights

AVERAGE NO. OF LIKES

**Content Feed**

How to update constraint in nonlinear optimization

Divide into 3 sub-problems. Solve with the constraints (1) y<=20 and NLcon (2) 20<=x<=40, y<=20, and NLcon (3) y>=20 and NLco...

1 dag ago | 0

| accepted

Im trying to run fsolve inside a for loop but it seem that my second iteration inside the for loop is not able to read the initial trial point

Should the division be by Afull(i)? F = @(GG)[slopeACdisp(i)-((GG(2)-Cdispy)/(GG(1)-Cdispx(i))); -tau+(0.5*abs((G...

1 dag ago | 0

Accessing (interpolating?) data in 3D array

You could use griddedInterpolant() array=rand(290,480,90); F=griddedInterpolant(array); extract=F({linspace(4,8,10), 400:...

2 dagen ago | 0

| accepted

Problem with parfor with two variables

Do you need to see the toc output in real time? If not, just save it until later: %% My code Y_1 =nan(N,numel(alpha),numel(bet...

3 dagen ago | 0

Converting Structure into 3d Matrix

Matrix=cat(3, all_frames.Frame); However, you will need generous RAM. Your all_frames structure already consumes about 5 GB in...

3 dagen ago | 0

| accepted

Optimization Problem but don't have closed form expression

The problem is that I dont have a closed form expression for B_k in terms of μ_k. if I have a set of values for μ_k to get the c...

3 dagen ago | 0

how to generate integer sequence number by logistic map?

function [z] =logistic(r,N) %sequence is chaotic where 3.57 < r < 4. %r = 3.8; % r parameter for chaotic regime %size ; % siz...

3 dagen ago | 1

| accepted

circle inside triangle tangent points

You can find the circle using incircle in this FEX submission https://www.mathworks.com/matlabcentral/fileexchange/34767-a-suit...

4 dagen ago | 0

fmincon gets very slow after few time

A few more performance optimizations that you should consider: maps = zeros(rows,columns,3,'single'); %<------ post conversio...

4 dagen ago | 1

fmincon gets very slow after few time

I suspect samsid() is just not as smooth or well-conditioned as mse() for some pixels, and therefore takes more iterations to te...

4 dagen ago | 0

Question

Restore toolbar buttons to app after migration from GUIDE

After using the Guide-to-AppDesigner migration tool, my app no longer has the standard figure toolbar buttons in the app figure ...

4 dagen ago | 0 answers | 0

### 0

answersFinding intersection points in a square.

Yes, you can use, https://www.mathworks.com/matlabcentral/fileexchange/93470-intersections-of-multiple-2d-lines-or-line-segment...

5 dagen ago | 0

Trying to understand behavior of holes in alphaShapes.

I found the following in posted material for a course at Stanford. It's a pretty intuitive explanation of how alpha shapes work,...

5 dagen ago | 0

| accepted

Function to compute product of all numbers from 1 to n

integerproduct(5) function r = integerproduct (n) if n==1, r=1; return; end r=n*integerproduct(n-1); end

5 dagen ago | 0

| accepted

Replacing Negative Values in Table with Previous Value in Column

T(:, {'D', 'E'}) = num2cell( fillmissing([D,E], 'previous') );

5 dagen ago | 0

| accepted

How do I create a 2D mesh of triangular elements?

Yes. Or triplot().

5 dagen ago | 0

| accepted

How do I turn off predictive text?

I've changed the Automatic Completion preferences, but it's still there. There is a different Automatic Completion section for...

6 dagen ago | 1

| accepted

How to concatenate output of objective function for lsqcurvefit?

c0 = [ic_arg{1}(x).'; ic_arg{2}(x).'; ic_arg{3}(x).'];

6 dagen ago | 0

| accepted

Saving outputs of a funtion inside nested for loop in organized fashion

Instead of returning 20 separate outputs, you could have paramA return them as fields of a struct. Then you could save each outp...

6 dagen ago | 0

Using bsxfun to plot

Now idea why you think bsxfun should be involved. Why not just, t=linspace(-2,2,n); plot(t,signal,t,filtsig)

6 dagen ago | 0

is there a function that receives 3 coordinates in X-Y as a matrix and calculates its Area and environment ?

p=polyshape(yourPoints); area(p) perimeter(p) centroid(p)

6 dagen ago | 1

| accepted

Remove duplicate points by Uniquetol

uniquetol(xy, 1, 'ByRows', true,'DataScale',[1,1]) % or

6 dagen ago | 0

| accepted

Submitted

Further tools for analyzing objects in N-dimensional images

A collection of tools to supplement bwpropfilt, bwareaopen, and the like.

6 dagen ago | 3 downloads |

Solving a large number (thousands) of different "Ax=b" equations when the matrices A are all the same small size (3x3 to 6x6), but different numbers.

If you have the Parallel Computing Toolbox, you can use pagefun(@mldivide,A,b) https://www.mathworks.com/help/parallel-comput...

6 dagen ago | 0

Solving a large number (thousands) of different "Ax=b" equations when the matrices A are all the same small size (3x3 to 6x6), but different numbers.

I suspect that a for loop will be fastest, but you could also try combining them into a single set of equations using, A=blkdia...

6 dagen ago | 0

| accepted

For loop with 2 variables

parfor k =1:N^2 [i,j]=ind2sub([N,N],k); .... end

7 dagen ago | 0

| accepted

Fminsearch curve fitting does not fit properly

Plotting your function in an interval around bmin shows that it is a minimum of the function you've provided. So, fminsearch did...

7 dagen ago | 0

| accepted

Question

Trying to understand behavior of holes in alphaShapes.

I have created the attached alphaShape object, which contains a hole. load alph_shape; shp plot(shp) I am trying to unders...

7 dagen ago | 2 answers | 0

### 2

answersAccuracy of polygon approximation

Perhaps the Dice Coefficient would be an appropriate metric. This would be a very easy calculation if the shapes are stored as p...

8 dagen ago | 0

Replace loop to create a matrix

This might be a more efficient way to build arg, but I suspect that your bottleneck will be in blkdiag(). function f = denomina...

8 dagen ago | 1

| accepted