Matt J

Last seen: 1 day ago | 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
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...

15 hours 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...

21 hours ago | 0

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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(:)

24 hours ago | 0

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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 =...

1 day ago | 1

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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',...

3 days ago | 0

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

3 days ago | 0

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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...

4 days ago | 1

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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=[""...

4 days 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...

4 days ago | 0

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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...

4 days ago | 0

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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...

4 days ago | 0

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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...

4 days ago | 0

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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 ... ...

4 days 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...

4 days 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]; ...

4 days ago | 1

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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...

4 days 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...

4 days 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...

5 days ago | 0

Answered
Matrix-vector operations without loops
A=2*(HessW(:,:)*GradW(:));

5 days ago | 0

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Answered
Linear fitting with 2 variables
Assuming f is 3x1, x=rand(1,15); %Example data f=rand(3,1); y=3*x+2+7*f; [F,X]=ndgrid(f,x); p=num2cell( [X(:), X(:).^0...

5 days ago | 1

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Answered
I want to implement these equations in MATLAB but how?
fn=@(theta,k) exp((0:k-1).' * (2i*pi*d/lambda*sin(theta))); A=fn(theta,M); B=fn(theta,N); y=reshape( A*B.', [],1);

5 days ago | 0

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Answered
How to get the camera scale factor
To get that, you need to image an object of known length at some known reference depth from the camera. You would also need to k...

5 days ago | 0

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Answered
solution of transcedental equation
eps1 = 1.5471; eps2 = 1.5431; eps1m = -9.894 ; eps2m = 1.0458; epsm = eps1m + i*eps2m; lambda = 633; k0 = (2*pi)/lambda;...

5 days ago | 0

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Calculate the Median of the results from 100 Simulations
impOOB=rand(100,5) median(impOOB,1)

5 days ago | 0

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Answered
how to plot inequality and their intersection ?
The region prescribed by your inequalities is unbounded, so it is not clear what it means to "plot" it. If you really meant x<=2...

5 days ago | 0

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How to rotate a 2d plot about the z axis to create a 3d object
See the cylinder command. https://www.mathworks.com/help/matlab/ref/cylinder.html t = 0:pi/10:2*pi; r = 2 + cos(t); [X,Y,Z]...

5 days ago | 0

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Answered
Randomly selecting a number from different arrays
A = [11 11 11 12 12 12 13 13]; B = [21 21 21 22 22 22 23 23]; C = [31 31 31 32 32 32 33 33]; M=[A;B;C]; I=mod(cumsum(ran...

5 days ago | 0

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How solve an equation in MATLAB?
c=A\y;

6 days ago | 0

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fmincon and the Objective function returned NaN warning
The sqp algorithm can recover from NaNs and Infs if your objective and constraint functions are finite on an open domain of x (I...

6 days ago | 0

Answered
Could you please help me to fit 2 circles so as to detect left and right half of breast?
Seems to me that you don't need to fit a circle, but rather to find the minimum bounding circle. For that, you could try minboun...

6 days ago | 1

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