# 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**7**

of 242,970

REPUTATION**20,804**

CONTRIBUTIONS

**193** Questions

**8,191** Answers

ANSWER ACCEPTANCE **
75.65%
**

VOTES RECEIVED**2,785**

RANK**263** of 16,987

REPUTATION**5,170**

AVERAGE RATING**4.90**

CONTRIBUTIONS**33** Files

DOWNLOADS **283**

ALL TIME DOWNLOADS**43610**

CONTRIBUTIONS**0 Posts**

CONTRIBUTIONS**0** Public Channels

AVERAGE RATING

CONTRIBUTIONS**0** Highlights

AVERAGE NO. OF LIKES

**Content Feed**

Non convex objective funtion

I'm not sure why the non-convexity is supposed to be an issue. fmincon itself does not rely on any convexity assumptions. In ...

4 hours ago | 0

combining results into a single matrix

One way. h = [1 2 3 4 5]; n=numel(h); m=n-2; First_Matrix=toeplitz([1,zeros(1,m-1)] ,[1 1 1 zeros(1,n-3)]).*h

13 hours ago | 0

| accepted

How do a cell2mat conversion for a non-uniform cell to a matrix

cell2mat(DD(:))

13 hours ago | 0

How to make a variable negative if another variable is negative?

X1=X.*sign(Y);

20 hours ago | 0

| accepted

Intersection of two lines

You need a least squares solution, since lines in 3D do not generally intersect. Assuming your point data are in column-vector f...

1 day ago | 0

| accepted

Plotting the solutions of an equation (rotated ellipsoid)

If you have the center, radii, and yaw-pitch-roll angles (in degrees) of the ellipsoid, you can plot a data-free ellipsoidalFit ...

1 day ago | 0

Create a 2x3 matrix named mat_B from the first and 2nd rows, and the 2nd, 3rd and 4th columns of the matrix C.

Looks right to me.

1 day ago | 0

| accepted

I dont understand why my table is displaying 1x1 sym and not a numerical value

You seem to be under the impression that vpa() converts a sym to a number. What you really want to do is use matlabFunction() to...

1 day ago | 0

| accepted

How can I create a set of N diagnal matrices range from diag(1, 1, ... , 1) to diag(-1, -1, ... , -1) for testing purposes?

Do you really need all Z{i} at the same time? [C{1:N}]=ndgrid([-1,1]); C=reshape( cat(N+1,C{:}) ,[],N); Z=zeros(N^2,2^N); ...

2 days ago | 1

| accepted

Non-linear constraints with several input variables in fmincon

Your nonlinear constraints are not differentiable. That doesn't always spell disaster, but it breaks the assumptions of fmincon....

2 days ago | 0

fsolve, fmincon producing different results

Do they both achieve the same objective value? If so, you simply have multiple solutions.

2 days ago | 0

How to extract columns from multiple 3D arrays?

Seems like you could just put them in a matrix: F=[f1(:), f2(:),f3(:),...,f7(:)]

2 days ago | 0

| accepted

How to Solve matrix equations in Matlab

With an over-determined system (3 equations and only 2 unknowns), you can't expect an exact solution. However, the solution that...

2 days ago | 1

| accepted

Efficiently assigning class property in a quadruple loop?

You've not told us the dependence of myLogicalVector and someFixedValue* on the loop variables, which is probably super-importa...

4 days ago | 0

Double Summation without using fft2 function

You can find examples of for-loop construction here, https://www.mathworks.com/help/matlab/ref/for.html#buhafgy-3

4 days ago | 0

| accepted

Sequence 1, 2, 4, 12

One possibility: p=[0.833333333333333 -4.499999999999996 8.666666666666661 -3.999999999999996]; polyval(p,1:4) polyval(...

5 days ago | 0

How to get optimal linear scaling factor for a set of vectors

I want to determine a linear scale factor for each y_raw? vector, such that the mean squared error (MSE) between the average of ...

5 days ago | 0

| accepted

Linear Equations infinite solutions parametric form

x0=pinv(A)*b; B=null(A); sol=@(c)x0+B*c;

5 days ago | 1

| accepted

Submitted

Further tools for analyzing objects in N-dimensional images

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

5 days ago | 6 downloads |

How can I speed up (or avoid) a comparison in for loop?

You might try bwlareaopenn from this submission https://www.mathworks.com/matlabcentral/fileexchange/90762-further-tools-for-an...

5 days ago | 1

Solver based optimization passing extra parameters

nonlcon=@(x)constraintFcn(x,aa) See also, Passing Extra Parameters - MATLAB & Simulink

5 days ago | 0

How to get the file names that start with the same letter in the folder?

For example, s=dir('T*_imag.bin'); fileNames={s([s.isdir]==0).name}

5 days ago | 0

Matrix form for creation and annihilation operator with spins.

Not sure this will help, but if you can write a function that implements the operator, then his File Exchange offering, https:/...

5 days ago | 0

What should go in a next-generation MATLAB X?

My wish list: (1) Colon operator produces column vectors, not row vectors: x=1:4 (2) Optimization Toolbox solvers should ha...

5 days ago | 2

combine different size vectors into one matrix

I will assume you have the vectors in a cell array C={[2 3 4 5]; [4 7 7]; [8 8 7 4 2 5]} Then, you can simply do, z=...

5 days ago | 0

using fsolve function to solve for 2 unknowns

x0 = [80,110]; [sol, Fsol] = fsolve(@problem_one,x0), function F = problem_one(theta) theta3 = theta(1); theta4 ...

7 days ago | 1

| accepted

fminunc initial point is local minimum, but fminsearch returns reasonable estaimtes

It could happen if your objective function is piece-wise flat (and hence non-differentiable). fminsearch is a derivative-free so...

7 days ago | 0

| accepted

How can I obtain the Fourier Transformation as a product of matrices?

N = (0:255).'; X = (2*cos(((15.8*pi)/128)*N)) + (3*sin(((27.3*pi)/128)*N)); F=fft( eye(numel(X)), [],1); fX = fft(X); %...

7 days ago | 0

| accepted