# Matt J

Professional Interests: medical image processing, optimization algorithms

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**Content Feed**

How can I increase the number of Fourier frequencies by adding 500 zeros to the end of the 27-sample-long signal ??

L = length(t)+500; fftx1=fft(x1, L)

2 hours ago | 0

Matlab does not find new method in class folder without "clear classes"

I don't know if it's intended or not, but my experience is that it only happens when your class is in a @-directory. If you put ...

3 hours ago | 0

Finding consecutive zeros in an array. Not able to solve using diff command

Using, https://www.mathworks.com/matlabcentral/fileexchange/78008-tools-for-processing-consecutive-repetitions-in-vectors [~,~...

3 hours ago | 0

Solve equation with multiple values for V

Because there is no analytical solution. Try vpasolve() or fzero() instead.

3 hours ago | 0

Help. Plot graph calculation

You mean, how to plot the triangle? You can do, x=linspace(0,3,1000); y=(1-abs(x-1)); y=y.*(y>=0); plot(x,y)

8 hours ago | 0

Intensity Profile of a specific line

You could just use improfile() https://www.mathworks.com/help/images/ref/improfile.html

8 hours ago | 0

Multiple plots on the same graph

I think the line where you plot is supposed to look like, semilogx(tc,PDF); but the code you've posted contains no variable c...

8 hours ago | 0

How to get rid of this line that connects the last and first point, I have made it white so its barely visible, but is there a way to not plot it?

plot3 (WayPTS(:,1), WayPTS(:,2), WayPTS(:,3),'black');

8 hours ago | 0

How to create a custom Matrix following a set of parameters

n=5; A=-diff(eye(n+2),2,1); A(:,1)=[]

8 hours ago | 0

How to create a custom Matrix following a set of parameters

n=5; c=[2,-1,zeros(1,n-2)]; r=[c,0]; A=toeplitz(c,r)

8 hours ago | 0

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How to covert a 1D vector to 2D matrix with overlapping effectively?

X=randi(30, 1,14); segment_size = 4; overlap_rate = 0.5; d=segment_size*overlap_rate; idx=(1:segment_size)'+ ( 0:d:(num...

17 hours ago | 0

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Plot elements of specific size

You could probably use a listener to increase the MarkerSize etc as a response to zooming in or out. The code below is an imple...

20 hours ago | 1

Plot elements of specific size

First, I don't care about interactive zooming. I'd like to save a pdf. If the zooming is happening only after the pdf conversio...

23 hours ago | 0

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how to write a function which converts graphs from linear scale to logarithmic scale and plot them both?

To convert the scale of an existing graph from linear to log, you can do, set(gca,'YScale','log') set(gca,'XScale','log')

24 hours ago | 0

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Cropping the same roipoly for multiple images

I don't understand what you mean by "cropping" an image to a non-rectangular region. An image, cropped or otherwise, is an inher...

1 day ago | 0

Calculating value of function in point

f=@(x)2*x+2.^x; test = evaluate(f,0,6,7) function matrix = evaluate(f,x,y,n) a = linspace(x,y,n); b = f(a); matrix = [a;b...

1 day ago | 0

Failure in initial objective function evaluation. FSOLVE cannot continue.

Is there supposed to be a '+' after teta1s? fval(2,1)=beta1c+teta1s+((2.66*mumr...

1 day ago | 0

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How to write a function with logical condition which takes an array and turns back an array?

K=sinc(alpha/pi*(x-y.'));

1 day ago | 1

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2D matrix multiply with 3D array

[m,n,p]=size(B); Br=reshape(B,[],p); Br=Br(:,1:200); %might not be necessary U1=Br*u; V1=Br*v; c=reshape( sum(U1.*V...

1 day ago | 0

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using eig to find the eigenvalues and eigenvectors of a large matrix on GPU

It might be a question of your hardware. On the GTX 1050 in R2020b, I see only about a 10% speed-up in double precision and abou...

1 day ago | 0

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A function does not work with an array as an input argument

args={'ArrayValued',1}; MyFun = @(a, x) ( integral(@(k) k .* (1 ./ ( 1 + (a*k - x).^2 )), -1, 1,args{:}) ./ ... integral(@(k...

2 days ago | 1

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Rounding errors when using quadprog

There's nothing wrong with post-rounding, however setting lb(i)=ub(i)=0 for the appropriate variables should force them to an ex...

2 days ago | 0

Connect the optimizer function to data extracted from another software

You've written a fitness function f=@(~) e_and_r_vals(md_e,E_best_vals_from_md_r) which takes no input arguments. The fitness ...

2 days ago | 0

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Is there an alternative to eval in a struct?

Your data organization seems like it should be reconsidered. In a struct, it doesn't make sense if different fields have essenti...

3 days ago | 0

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Expressing polynomial including a indefinite parameter

Possibly you mean that you want a coefficient vector as the output, rather than a polynomial in functional form. syms a x P ...

3 days ago | 0

Expressing polynomial including a indefinite parameter

One way. p = @(x,a) polyval([a,-4,2-a],x); Usage: x=1; a=2; p(x,a)

3 days ago | 1

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Combining 3 2D graphs into a 3D figure

Something like the following, perhaps? x=linspace(0,5); z1=x.*exp(-x); z2=3*x.*exp(-4*x); Hax=axes; area(x,z1,'Parent',up...

3 days ago | 0

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How can I minimize absolue value in a power optimprob?

The objective is to minimize the integral of Pgrid abs value... while the control variables are Pbatt and Pev; Ppv and Pload If...

3 days ago | 0

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Finding out what initial guesses the curve fitting toolbox made for curve fit

I don't think there's anyway to dig out the initial guess generated inside fit(), but why not just specify your own random start...

4 days ago | 0

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