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Matt J


Last seen: Today Active 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
Fit dataset to another dataset
See polyfit(). https://www.mathworks.com/help/matlab/ref/polyfit.html

alrededor de 3 horas ago | 0

Answered
optimization of matrices with random initialization
Make sure your objective function code does not contain any randomization steps. Your initial guess can be random, but the objec...

alrededor de 3 horas ago | 0

Answered
HOW TO REVERSE THE BINARY IMAGES
outt33(:,:,i) = ~imbinarize( I)

alrededor de 3 horas ago | 0

Answered
How do I obtain FFT of nabla operator F(▽)?
nable=diff(eye(N)); %diff in operator form operator=fft(nabla.'*nabla);

alrededor de 3 horas ago | 0

Answered
What dose this function mean and what is the differentes ?
The first is calculating the number of zeros in B and the second is summing all values in B (times -1).

alrededor de 4 horas ago | 0

Answered
Error in lsqcurvefit with 3 unknown parameters involved
If your model has 3 unknown parameters, then your initial guess P40 must be a vector of length 3.

alrededor de 4 horas ago | 0

| accepted

Answered
sum only consecutive 1's in matrix
See, Tools for Processing Consecutive Repetitions in Vectors https://www.mathworks.com/matlabcentral/fileexchange/78008-tools...

alrededor de 5 horas ago | 0

Answered
what is the fastest appproach to solve a system of non linear equations ?
Seems like it would make sense to regard this as a system of 100K simultaneous equations and solve for the PDE parameter with ls...

alrededor de 21 horas ago | 0

Answered
How do we allocate equidistant points on a sinusoidal curve?
You should also have a look at interparc() https://www.mathworks.com/matlabcentral/fileexchange/34874-interparc?s_tid=srchtitle...

alrededor de 21 horas ago | 0

Answered
How do we allocate equidistant points on a sinusoidal curve?
You can use fzero, x_p=0; y=@(x) -25*sin((2*pi/50)*x); fun=@(d) d.^4+( y(x_p+d^2)-y(x_p)).^2 - 0.004^2; x=x_p+fzero(fu...

alrededor de 21 horas ago | 1

| accepted

Answered
drawrectangle draws rectangle even though the mouse is clicked outside the parent UIAxes
You can fall back to imrect, if necessary fcn = makeConstrainToRectFcn('imrect',get(gca,'XLim'),get(gca,'YLim')); h=imrect('Po...

alrededor de 21 horas ago | 0

Answered
create nononteger random matrix in certain range
200*rand(5)-100

alrededor de 21 horas ago | 1

| accepted

Answered
Array processing using Taylor Series and FOR Loops to approximate sin value for each element in that array.
The array can be of any type and dimensions. If so, why does your code assume it will be 2D? Can't it be 3D or 4D? In any case...

1 día ago | 0

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Answered
How to store iterative information to a matrix?
The following is pretty typical. result=nan(big_number,1); while abs(y)>=small_number &iteration<big_number [x,y] = some...

2 días ago | 0

Answered
how to generate points inside a rectangle not parallel to axis in Matlab
You mean you want to generate N random points? If so, then, xy=Q*([length;width].*(rand(2,N)-0.5)) + center(:)

2 días ago | 0

| accepted

Answered
How do I add zero padding to this convolution?
Not sure what the question is, but you can easily compare your result to direct convolution to see if it's correct. x1x2_conv =...

3 días ago | 1

Answered
How to tell an multi-output anonymous function to vectorize its output components which are constant
One way, f=@(x,y) completeRows({x+y;2;x*y;x.^2-1;3}); f([1 2],3) function out=completeRows(C) n=max(cellfun('length',...

4 días ago | 0

Answered
Area between three curves
A=Einspeiseanteil; B=GabelstaplerP; C=max(A,B); area=trapz(X,(C-Y).*(C>=Y))

4 días ago | 0

Answered
How to plot vectors exactly on the edge of another graph?
t=linspace(0,360,91); t(end)=0; u=cosd(t); v=sind(t); fimplicit(@(a,b) a.^2+b.^2-1);hold on quiver(u,v,u,v,'Color','r...

5 días ago | 1

| accepted

Answered
How can I assign values to min/max of a column within each value of another column?
Let's call your table T, then, T=table(randi(2,10,1), randi(100,10,1), rand(10,1),'V',{'Device','Time','current'}) str=[""...

5 días ago | 0

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Answered
min and max optimization as a single minimization function
if i am adding these function together like as follows min(f)=(1/f1)+f2 will it be correct? can i get the proper result? The s...

5 días ago | 0

Answered
4D matrix multiplication
steer=reshape( permute(steer,[2,3,4,1]),101^2,[],136 ); R=permute(R,[2,3,1]); F=1./sum( pagemtimes(conj(steer),R).*steer, 2...

5 días ago | 0

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Answered
plotting two lines intersecting at a certain point
This is equivalent to a first order free-knot spline fit. This FEX submission might be useful, https://www.mathworks.com/matlab...

5 días ago | 0

Answered
how do you create an array of 3d arrays
I've been trying different ways of using the cat function You haven't told us in what form the 15 stacks exist now. If you have...

5 días ago | 0

Answered
How to grow a vector in a loop?
coef=nan((ldiv+1)^2*(sdiv+1)^2,1); %PRE-ALLOCATE mm=0; for ii = 1:ldiv+1 for jj = 1:sdiv+1 ... ...

5 días ago | 0

Answered
Frequency Domain Filtering by Convolution Theorem
They are warnings, not errors, but if you expect your FFT/IFFT to be real-valued due to symmetry, you can do h2 = ifft2(h1,'sym...

5 días ago | 1

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Answered
How to grow a vector in a loop?
You could just vectorize everything. x_m = [sb_panel.xm]; y_m = [sb_panel.ym]; z_m = [sb_panel.zm]; ...

5 días ago | 1

| accepted

Answered
Efficient computation of the sum of pairwise absolute differences
This GPU implementation may also be useful. I was able to process a 500x500 matrix in 20 seconds on the GTX 1080 Ti. A = magi...

5 días ago | 0

Answered
Efficient computation of the sum of pairwise absolute differences
I think parallelization might be the only way to accelerate things. Parfor seems to work well with the rewritten version of diff...

6 días ago | 1

Answered
Efficient computation of the sum of pairwise absolute differences
The question: is there any way to make this work efficiently, ideally with conv2 or xcorr2? If you were taking the sum of squa...

6 días ago | 0

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