# Matt J

Professional Interests: medical image processing, optimization algorithms

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**Content Feed**

Normalization of matrix column

In recent Matlab, A= [ 1 2 3 4 3 4 5 6 4 5 6 7 ]; A=normalize(A,1,'range')

alrededor de 13 horas ago | 1

Normalization of matrix column

a=min(A,[],1); b=max(A,[],1); A=(A-a)./(b-a);

alrededor de 13 horas ago | 0

How can I separate objects in a Binary Image?

What if you use regionprops to find the minor axis of the ellipse-shaped blobs and split them along that axis?

alrededor de 21 horas ago | 0

fsolve stopped because the problem appears regular

If you are going to solve for x(i) that are expected to be on the order of 1e15, you need to adjust all of fsolve's tolerance pa...

alrededor de 23 horas ago | 0

fit function not iterating

You should adjust your units for both the x,y data and for the parameters so that the datay are not so uniformly close to 0 and ...

1 día ago | 0

How to fit a smooth curve to data in 3D?

Perhaps with csaps(). There, you have parameters that directly control the level of smoothing.

1 día ago | 0

How to plot three X & Y sets of points on the one graph from a text file

plot( Ifile(:,[2,4,6]) , Ifile(:,[3,5,7]) )

1 día ago | 0

| accepted

How can I separate a sorted array into multiple at points referenced by another array?

This might be what you want: A = [1 4 7 9]; B = [1 2 3 4 5 6 7 8 9 10 11 12 13]; G=discretize(B,[A,inf]); C=splitapply(@...

1 día ago | 0

| accepted

How can one reshape this table?

Perhaps as follows? load tst T [Gage,IDage]=findgroups(T(:,1)); [Gdate,IDdate]=findgroups(T(:,2)); Tnew=[ IDdate, a...

1 día ago | 0

| accepted

Getting different results from function handle & syms for a same equation. How to avoid it?

The results are different because the polynomial coefficients are different: >> sym2poly(P)-coeffs' ans = 1.0e-04 * ...

1 día ago | 0

How to "quicksave" a file in app designer?

The 3rd argument to uiputfile should end with a path separation character: [file,path] = uiputfile(".mat","Save AnimTronics Sys...

1 día ago | 0

how convert the vector to matrix ? unknown number of columns

No, the solution is ill-defined. Another result with the same number of rows is: A=[1 2 3 4 5 6 7 8 9]

2 días ago | 0

Applying vectorization techniques to speedup the performance of dividing a 3D matrix by a 2D matrix

Another idea. clc; clear all; % Test Data % I'm trying to remove the for loop for j in the code below N = 10; M = 10; Nx...

2 días ago | 1

Applying vectorization techniques to speedup the performance of dividing a 3D matrix by a 2D matrix

On the GPU (i.e. if A and b are gpuArrays), the for-loop can be removed: Uhat = permute( pagefun(@mldivide,A,reshape(b,[],1,Nx)...

3 días ago | 0

Finding the vertical offset of a gaussian fit

This File Exchange routine does gaussian+constant fitting: https://www.mathworks.com/matlabcentral/fileexchange/69116-gaussfitn...

3 días ago | 0

| accepted

How to set a custom equation to fit 5 points in space by fitsurface?

I can't find "fitsurface" in the Mathworks documentation, but the fit is easy enough to do algebraically. x=x(:); y=y(:); z=z(:...

3 días ago | 0

Why is x(:) so much slower than reshape(x,N,1) with complex arrays?

The following simple test seems to support @Bruno Luong's conjecture that (:) results in data copying. The data of B1 resulting ...

4 días ago | 1

Is it possible to correctly perform a multi-dimensional FFT on a 1D linearised version of a 3D array?

Reshaping to and from 3D format should not add significant cost: Nx = 256; Ny = 256; Nz = 128; N = Nx*Ny*Nz; A0 = rand(N,1)...

4 días ago | 0

| accepted

Question

Why is x(:) so much slower than reshape(x,N,1) with complex arrays?

The two for loops below differ only in the flattening operation used to obtain A_1D . Why is the run time so much worse with A_3...

4 días ago | 3 answers | 2

### 3

answerssee the 3d image and see the coordinates while moving the mouse over the image

You can use imshow() to display any particular slice of the image and then use the axis datatip button to get the in-slice 2D co...

5 días ago | 0

How do i find the coordinates of a boundary

How about simply, [m,n]=size(Image); I=boundary(:,1); J=boundary(:,2); corner1 = [1, max(J(I==1))]; %row/column coordinat...

5 días ago | 0

How to Draw an ellipsoid between two 3d coordinates

Another way would be to use the ellipsoidalFit.groundTruth method in this File Exchange submission. https://www.mathworks.com/m...

5 días ago | 0

Trying to count the number of pixels in an image over a specific RBG value

results.area=nnz(imstd>90);

5 días ago | 0

| accepted

Normally distributed random numbers with fixed sum

Why not simply, x(1:N-1)=randn(1,N-1); x(N)=fixedValue-sum(x(1:N-1))

5 días ago | 0

Only analyze what is outlined in black in an image

If you have a binary mask of the circles, you can just do numBlack = nnz( circles & ~BW ); numWhite = nnz( circles & BW);

5 días ago | 0

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If the quadprog problem is infeasible, how i can solve it with a certain tolerance?

It never really makes sense to have more equality constraints (here 36) than you do unknowns ( here 6). In order for the problem...

7 días ago | 0

| accepted

How to construct a "ones" matrix with zero blocks in the diagonal

repelem(1-eye(4),4,4)

8 días ago | 1

Iterative solution of non-linear equation with a provided guess value?

You could use fzero's OutputFcn option https://www.mathworks.com/help/optim/ug/fzero.html#btn3z5s-options to access the sequen...

8 días ago | 0

Iterative solution of non-linear equation with a provided guess value?

Using fsolve() instead of fzero(), you could solve the problem as a system of two equations in two unknowns. The two unknowns ar...

8 días ago | 0

Failure in initial user-supplied nonlinear constraint function evaluation

One problem: nonlcon = @simple_constraint; There is no function called 'simple_constraint' in your attached script. There is a...

9 días ago | 1

| accepted