# Matt J

Professional Interests: medical image processing, optimization algorithms

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**Content Feed**

Checking inverse of convolution theorem

You need to use circulant convolution, rather than linear convolution. Also, your fftshift must be applied to the output of the ...

6 hours ago | 1

| accepted

How to Reduce image size and increase size

Here is an example, https://www.mathworks.com/help/matlab/ref/imresize.html#mw_0a904a96-3d99-4878-b28f-cdf6f0d7ca0c

9 hours ago | 0

Why do I get Cannot fit Power functions to data where X has nonpositive values when using the curve fitting tool?

Torsten's idea for an exp1 fit works pretty well. load myfile f=fit(x,y,'exp1'); plot(f,x,y)

10 hours ago | 0

Make optimiser more robust to upper and lower bounds

The problem might be due to insufficient or low quality data. The optimizer is therefore relying more on the bounds than the phy...

22 hours ago | 0

I want to only interpolate shorter amounts of data and leave the longer amounts of NaN not interpolated.

If more than x NaN's in a row, then do not interpolate that chunk of data Using function from here, https://www.mathworks.com...

23 hours ago | 0

How do I extract each value from a column matrix and subsitute in a equation?

Change all of your '*' operators to elementwise operator '.*' res=@(z) reshape(z,1,1,[]); phi = res( comb(1,:) ); theta = r...

1 day ago | 0

| accepted

Extracting a subset from the Faces and Vertices

[m,n]=size(FacesSub); [Indices,~,FacesSub]=unique(FacesSub); FacesSub=reshape(FacesSub,m,n); VerticesSub = Vertices(Ind...

1 day ago | 0

| accepted

Gamultibojective Problem "Not enough input arguments." Error

x = gamultiobj(@my_objfunction,2);

1 day ago | 0

| accepted

Why does my for loop cause MATLAB to not stop running?

In the code as you've posted it, the for-loop is never closed by an "end". That would prevent it from continuing to the next ite...

1 day ago | 1

| accepted

Plot an ellipse using an equation

fimplicit(@(x,y) 4*x.^2 +25*y.^2 - 32*x - 100*y+64)

2 days ago | 0

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implicit expansion for arrayfun

A=rand(10,5); B=3; C=rand(10,1); D=rand(1,5); args={A,B,C,D}; sz=cellfun(@size,args,'uni',0); maxsz=max(vertcat(sz{:})); ...

2 days ago | 0

Delete m consecutive rows every n rows

m = 6; n = 24; N = 87; data = (1:N).'+(0:10:20); % some data discard=repelem( [false;true] , [n;m], ceil(N/(m+n)) ); ...

2 days ago | 1

Run interpolation for several datasets at once

x and y used to be both vectors with constant spacing (x and y have their own spacing constant). which have been meshed. Let's...

2 days ago | 0

Run interpolation for several datasets at once

If it's gridded interpolation, you shouldn't be using griddata. You should be using interp2. for i=1:N x_Wake = x(:,:,i)...

2 days ago | 0

Write the MATLAB program using fzero

Documentation and examples for fzero: https://www.mathworks.com/help/matlab/ref/fzero.html

2 days ago | 0

How do I efficiently add values of same indices to a vector?

vec1=vec1+accumarray(ind(:),vec2(:),size(vec1));

2 days ago | 1

| accepted

Cropping 3D image into equal size

If the idea is to split A into cell array cells, using imcrop3 is a little over-elaborate. Consider using mat2cell or download m...

3 days ago | 0

| accepted

Help with linear optimisation problem

Diffs=abs(reshape(B,1,1,[])-A); d=min(Diffs,[],3); [Arows,Acols]=find(d==min(d(:)));

3 days ago | 0

Question

How does one set the PatientPosition and other spatial attributes when writing a dicom CT volume?

I am trying to write DICOMs of a CT volume in both single- and multi-file form. To check that the result is readable, I try read...

3 days ago | 0 answers | 0

### 0

answersHow to automatically obtain shape coordinates

Perhaps as follows load Image B=medfilt2(A,[5,5])<60; B=bwareafilt(B,5) & ~bwareafilt(B,1); T=regionprops('table',B,'Cen...

3 days ago | 0

Why is my array sending data back in E notation?

That's just the way Matlab displays things by default in the command window . There are other styles which you can set using the...

4 days ago | 1

| accepted

Define function with nonlinear equation system vercat error

F = @(x)[sqrt( (101 - x(1)).^2 + (16 - x(2)).^2 + (207 - x(3)).^2 )+ x(4)- 310.5685; sqrt( (52 - x(1)).^2 + (21 - x(2))....

4 days ago | 1

Solving a nonlinear equation using fsolve. cant reach at perfect result. output showing some error written below.

Result must be around 22-25. but itc coming .0029. As the plot shows, your function has no roots in the range 22-25 p = 1; ...

4 days ago | 0

| accepted

Short Length Convolution Speed Up

From the documentation, it appears that the faster performance of fftfilt is indeed expected: When the input signal is relati...

4 days ago | 0

| accepted

Short Length Convolution Speed Up

Do you have the Parallel Computing Toolbox and a decently powerful GPU? If so, filter() is enabled for gpuArrays.

4 days ago | 0

Using mat2cell

You can use mat2tiles from, https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-divide-array-into-equal-sized-...

4 days ago | 0

| accepted

Calculate log multiple columns

Your code is correct, assuming Germany_Greece is a matrix and not a table or some other data type.

4 days ago | 1

| accepted