Community Profile # Matt J

Last seen: Today Attivo dal 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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How to implement the Gaussian radial basis function in MATLAB ?
If you have the Statistics Toolbox, you can avoid a loop by using pdist2 Lt = 10; p = rand(Lt,4); sigma = 1.0; K=exp(-pdis...

circa 4 ore fa | 0

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How do I plot a prod function in MATLAB?

circa 6 ore fa | 0

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Concise way to remove columns of a matrix with at least 2 repeating values in separate rows
One possibilty, A =[ 2 8 1 8 2 3 1 7 5 4 5 4 2 6 3 1 ...

circa 6 ore fa | 0

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How to evaluate individual once at a time when using GA with parallel processing?
The objective function will always evaluate one point at a time unless you are using the UseVectorized option. As for your scre...

circa 13 ore fa | 0

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lsqnonlin initial conditions (transcendental equation)
You can split the model function into real and imaginary parts, func=@(a) [real(func(a)); imag(func(a))]; [k,resnorm,residua...

circa 13 ore fa | 0

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Why does fmincon using the sqp algorithm need a full matrix to specify linear constraints?
Probably because the SQP algorithm must extract subsets of rows of the constraint matrice quite often. This can be much faster f...

circa 15 ore fa | 1

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How can I ort elements of a column in a matrix using elements of another column in another matrix
subset=[1,3] %The vector of IDs with positive y-intercept idx=ismember(Matrix1(:,3),subset); Matrix1=Matrix1(idx,:);

circa 16 ore fa | 0

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solve non-linear equation
You can solve for x=e^(-z) using roots. Then use z=-log(x). Example: z=2.4; pho=2; L=2; G = exp(-z) + pho*exp(L-2*z); ...

circa 18 ore fa | 0

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How to build a function fun that takes as input the matrix A and as output provides the matrix B which is produced out of A in the following ways.

circa 18 ore fa | 0

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How to get gradient data from non-linear 2D plot
Yes, you can use the diff or gradient command.

circa 18 ore fa | 0

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When plot graph vertex labels cut the edges, how to avoid it?
You can remove the node labels as follows: h=plot(graph(bucky)); h.NodeLabel={};

circa 19 ore fa | 0

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How to get pixel value inside a circle
drawcircle() returns an object with a createMask method. Using the mask produced by createMask(), you can do, mean(yourImage(ma...

circa 19 ore fa | 0

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Find the centre and the radius of the circle or ellipse

circa 19 ore fa | 0

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Data show one value why all values not displying?
That's not unthinkable, if the points in the plot were generated one at a time and discarded: for fid=linspace(0.01,0.1185,10) ...

circa 20 ore fa | 1

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plot sfit shows an offset between data and the fit but the residuals are very small.
One thing that seems to be creating problems is that your model function returns different results depending on whether the (x,...

1 giorno fa | 0

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How to append a large number of cell arrays vertically?

1 giorno fa | 1

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Removing a part of curve
I'll demonstrate a technique using a simpler example, since only you know the mathematical meaning of the region to be excluded ...

1 giorno fa | 0

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Get the last rows of tables inside a cell array
There is no way to avoid the slow speed of a loop when dealing with cell arrays. Cell arrays are not meant to be fast. However, ...

2 giorni fa | 0

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Why do I get 'Array indices must be positive or logical values' in symsum function?
The error is because you appear to be indexing P with a non-integer. Did you mean to write, sin(n*P*(1-y/h)) ?

2 giorni fa | 0

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Calculate the conrast by the difference between the highest and lowest intensity value
You could use medfilt2 or medfilt3 to get rid of the outliers. You could then use discretize to bin the data into bins of width ...

2 giorni fa | 0

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Confidence and prediction bands using nlsqcurvefit
Covariance methods are not valid when you have parameter bound constraints. Since it's not a time-consuming fit, I would just us...

2 giorni fa | 0

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How to solve optimization problem using sequential minimal optimization (SMO) in MATLAB
There is this offering on the File Exchange, which I have never used, https://www.mathworks.com/matlabcentral/fileexchange/6310...

3 giorni fa | 0

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truncate at 10^-3
A few options: x=round(pi,3) y=floor(pi*1000)/1000 sprintf('%.3f',x) sprintf('%.3f',y)

3 giorni fa | 0

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Concatenate content of cells containing vectors
Simpler, yes. Faster, no. A{1,1} = 1 ; A{2,1} = 2 ; A{3,1} = [3 4 5 ]; B{1,1} = 10 ; B{2,1} = [ ]; ...

3 giorni fa | 1

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Did mldivide Implementation Change in R2022b?
The condition number of clsys.A is very poor, so you should not expect any consistency in the result among different implementat...

4 giorni fa | 2

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Gradient function not matching array dimensions

4 giorni fa | 0

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Gradient function not matching array dimensions
The expression for the gradient is very simple. Why not just apply the analytical expression on whatever meshgrid you are workin...

4 giorni fa | 0

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This code is taking a long time to finish. I tried with vectorizing the inner loops n=2:ny-1, m=2:nx-1, but it is still slow. Should I also vectorize the time loop?
Yes, there is no reason to be doing any looping when constructing the variables predictor and corrector. They can be computed in...

5 giorni fa | 0

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How do I use interp2 with mesh grid to backwards warp one image onto another to create a mosaic?
If you use imwarp instead of interp2, the OutputView setting can be used to specify where in the world coordinate system the tra...

5 giorni fa | 0

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How do I assign multiple variables the array data from multiple rows in a field
Is this what you mean? data={1,2,3,4,5,6}' [A,B,C,D,E,F]=deal(data{:})

5 giorni fa | 0

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