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Matt J


Last seen: Today
6.726 total contributions since 2009

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.

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Answered
Can I change degrees to radians by simply changing from sind to sin?
cos and sin will assume the input angles are measured in radians. If theta is in degrees, you must convert to radians in order t...

alrededor de 1 hora ago | 1

| accepted

Answered
How to use linear and quadratic programming to optimize w to solve the following problem
This looks like a direct application of lsqlin https://www.mathworks.com/help/optim/ug/lsqlin.html

alrededor de 2 horas ago | 0

Answered
count number of indices
Using group1s from the File Exchange https://www.mathworks.com/matlabcentral/fileexchange/78008-group1s col2=arrayA(:,2); I...

alrededor de 2 horas ago | 0

Submitted


Extract linearly independent subset of matrix columns
Loop-free code routine to find a maximal subset of linearly independent columns in a matrix

1 día ago | 3 downloads |

Answered
How do I partition a n by m matrix into equal rows
Hint: Consider repelem https://www.mathworks.com/help/matlab/ref/repelem.html

2 días ago | 0

Answered
Integral calculation using matlab
My difficulty stems from the absolute value which is "outside" of the integral Why is this a difficulty? Because it prevents yo...

2 días ago | 0

Answered
finite difference step size value in fmincon
You might try the sqp or interior point algorithm, instead of whatever fmincon algorithm setting you are currently using. Accord...

2 días ago | 0

| accepted

Answered
fmincon output is converging to infeasible point
It appears that you are simply trying to find a point where getCost(Y) returns zero. If so, it might make it easier on the algor...

2 días ago | 0

Answered
Algorithm to extract linearly dependent columns in a matrix
See this FEX contribution https://www.mathworks.com/matlabcentral/fileexchange/77437-extract-linearly-independent-subset-of-mat...

2 días ago | 2

Answered
fminbnd loop leads to same optimizer
In addition to hwat John said, you could plot the function to confirm whether fminbnd is giving you a good approximation of the ...

3 días ago | 0

| accepted

Answered
return a single vector after a for loop and not individual results
For a fully vectorized solution: [maxval,place]=max(Divergence<=5,[],2); place(maxval==0)=nan; Or, to do the same with a loop...

3 días ago | 0

| accepted

Answered
Index in position 1 exceeds array bounds (must not exceed 1). FMINCON
Make theta0 a column vector: >> theta0 = [2,0.2,0.1,0.4].' theta0 = 2.0000 0.2000 0.1000 0.4000

4 días ago | 0

| accepted

Answered
How can I determine the amount of times a certain value can be achieved by summing values in a matrix?
Below is a more advanced version of my original answer, which is showing greater empirical succes. It incorporates initializatio...

5 días ago | 0

Answered
How to logically index multiple indices while indexing other indices normally?
You probably won't notice much difference with such small data sizes, but reshape is slightly better than permute because it wil...

5 días ago | 0

| accepted

Answered
How do I get every combination of 3 vectors?
Example: [X,Y,Z]=ndgrid(1:3,10:15,100:102); [X(:),Y(:),Z(:)]

5 días ago | 1

Answered
Particularly strange bug using the eval function
I also know that MATHWORKS would prefer me not to define variables that clash with their own builtins. However, the code st...

5 días ago | 2

Answered
Can one set up initial values for fminbnd?
No, you cannot. However, you might get a comparable effect if you use fminsearch instead, setting your objective to Inf outside ...

5 días ago | 0

| accepted

Answered
Given a point, locate 3 point in different 8 directions.
Or maybe this is what you want. In the code below, A is your image and the result Neighbors(i,j,:) contains all 9 neighbors of A...

5 días ago | 0

Answered
calculate mean in a for loop
No need for loops, Mean_answer=cumsum(data,2)./(1:size(data,2));

5 días ago | 0

Answered
Given a point, locate 3 point in different 8 directions.
I'm not sure I understand what the how-to challenge is in the question, but the approach that I think you want is to calculate a...

5 días ago | 0

Answered
How can I determine the amount of times a certain value can be achieved by summing values in a matrix?
This solution (EDITED) requires the Optimization Toolbox: LengthVal = [50,50 ,60,70]; %User Input N=numel(LengthVal); X...

7 días ago | 1

Answered
System of equations: Two different versions of Matlab, with the same script, give different solutions
Seems to me that you are getting the same solutions for each fixed Current level, but presented to you in a different order depe...

7 días ago | 1

Answered
How to monitor the output of a function when being called in a separate function
You could return fileStr from the file as an output argument and perform whatever tests are needed in the calling workspace, e.g...

9 días ago | 0

| accepted

Answered
Fitness function increases rather than decreasing with fmincon using hybrid Genetic Algorithm
This might happen if your objective has discontinuities or non-differentiabilities. Such functions are outside the scope of fmin...

9 días ago | 0

| accepted

Answered
Can one run fminsearch for a function defined by cases?
Because you are optimizing over a known bounded interval fminbnd is more appropriate: x_optimal = fminbnd(@fun,0,2) function...

9 días ago | 1

| accepted

Answered
Automatically update attributes of a class ?
This has to go in a file called Rect.m : classdef Rect properties l,b end properties (Depen...

9 días ago | 1

| accepted

Answered
How to pass field values to subclass from superclass?
Your terminolgy is confusing, so I'm not completely sure I understand your question. "Classes" do not have property values. Only...

9 días ago | 0

Answered
How to use objects of one class in the methods of another class as input?
objc is a Matlab variable like any other, and therefore you can give it as input to a function or class method just like any oth...

9 días ago | 0

| accepted

Answered
maximizing a function of 2 variables where coefficients are given by parameters
You can use fminunc, for example, which would do this for you implicitly. Or, you can write down the first order optimality cond...

10 días ago | 0

Answered
Minimizing a scalar value using "fmincon" derived through many variables
Much is unclear from your post including what your unknowns are and how they determine shortprob. However, if S is a function of...

10 días ago | 1

| accepted

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