Matt J
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.
Statistics
Your submission is selected as "Pick of The Week"
Awarded to Matt J on 08 Oct 2021
Your submissions were downloaded 250 or more times in a month
Awarded to Matt J on 01 Nov 2019
Publish your first review
Awarded to Matt J on 09 Oct 2019
Your submissions received 25 five star ratings
Awarded to Matt J on 09 Oct 2019
Publish your first submission
Awarded to Matt J on 09 Oct 2019
Answer 50 questions that were unanswered for more than 30 days
Awarded to Matt J on 12 Oct 2017
Contribute at least one answer each month for 36 consecutive months
Awarded to Matt J on 20 Jul 2017
Accept 50 answers given by other contributors
Awarded to Matt J on 20 Jul 2017
100 of your answers have been accepted
Awarded to Matt J on 20 Jul 2017
Provide your first answer ever to someone else's question
Awarded to Matt J on 20 Jul 2017
Content Feed
How can I perform large sparse matrix multiplication efficiently when one sparse matrix is block diagonal?
Here's what I see in a simple test comparing ndSparse.sum() and ndSparse.summl() >> A=ndSparse.sprand([1e4,1e4,10],0.1); >> ...
26分 前 | 0
Commenting Code inside for loop. Orientation Issue
No, but enhancement requests for this have been submitted (by me at least).
1日 前 | 0
Custom class properties and method attributes
I don't know why it's not documented, but apparently there is a Description attribute that can be added, e.g., classdef myclass...
1日 前 | 1
| 採用済み
How do I get the indexes of a symmetrical logical matrix without getting repetitions of those indexes?
[I,J]=find(yourMatrix); keep=(J>=I); I=I(keep); J=J(keep);
1日 前 | 0
| 採用済み
calling seperate members of a vector function
There's no way to do that. You could do it if the components are held in struct form, e .g., F=@(x,y) struct('a',x-y,'b', y^2);...
2日 前 | 0
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)
3日 前 | 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日 前 | 1
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日 前 | 0
Solve equation with multiple values for V
Because there is no analytical solution. Try vpasolve() or fzero() instead.
3日 前 | 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)
3日 前 | 0
Intensity Profile of a specific line
You could just use improfile() https://www.mathworks.com/help/images/ref/improfile.html
3日 前 | 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...
3日 前 | 0
| 採用済み
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');
3日 前 | 0
How to create a custom Matrix following a set of parameters
n=5; A=-diff(eye(n+2),2,1); A(:,1)=[]
3日 前 | 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)
3日 前 | 0
| 採用済み
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...
4日 前 | 0
| 採用済み
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...
4日 前 | 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...
4日 前 | 0
| 採用済み
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')
4日 前 | 0
| 採用済み
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...
4日 前 | 0
| 採用済み
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...
4日 前 | 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...
4日 前 | 0
| 採用済み
How to write a function with logical condition which takes an array and turns back an array?
K=sinc(alpha/pi*(x-y.'));
4日 前 | 1
| 採用済み
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...
4日 前 | 0
| 採用済み
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...
4日 前 | 0
| 採用済み
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...
5日 前 | 1
| 採用済み
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...
5日 前 | 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 ...
5日 前 | 0
| 採用済み
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...
6日 前 | 0
| 採用済み
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 ...
6日 前 | 0
