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# Matt J

Last seen: 1 día ago Active since 2009

Professional Interests: medical image processing, optimization algorithms

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Converting a system of coordinates
You need to measure the position of at least three non-colinear 3D points in both coordinate systems. Then, you can find the map...

1 día ago | 0

Extract sub array from d-dimensional array given indices for each dimension
If you have your vd_i in a cell array V={vd_1,vd_2,...,vd_d}, you can do A(V{:})

1 día ago | 0

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How to count numbers greater than a determined value
out = cumsum( histcounts(heights,0.5:0.1:100-eps(100)) ,'reverse');

1 día ago | 0

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Take data out of a structure horizontally
Transpose the matrices.

1 día ago | 0

Change initial step length in fmincon
You have some control over the step distance used for finite differencing operations (through FiniteDifferenceStepSize), and for...

1 día ago | 0

Meshgrid orthogonal to a line in 3D Space
You can also start with an unrotated grid, then rotate it: d=[1;1;1]; d=d(:).'/norm(d); [X,Y,Z]=meshgrid(-5:5); R=[d;null...

1 día ago | 0

Meshgrid orthogonal to a line in 3D Space
There are also ready-made File Exchange tools you can use, like this one d=[1;1;1]; %direction of line d=d(:)./norm(d); gtP...

1 día ago | 0

Meshgrid orthogonal to a line in 3D Space
Pick a 3D direction vector for the straight line, e.g. d=[1,1,1]; Then, d=d(:)./norm(d); B=null(d.'); %basis [x...

1 día ago | 0

how can i plot a continuous unit step function without heaviside?
Hint: t=linspace(-1,3,100); u=(t>1); plot(t,u); axis padded; xlabel t; ylabel u

2 días ago | 0

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Calculate mean value of every element of a .mat file
S = structfun( @mean, load('yourFile.mat'),'uni',0); matrix=cell2mat(struct2cell(S));

2 días ago | 0

program that performs 3D geometric transformations
imwarp will probably do most of the heavy-lifting for you. It's not clear to me what is meant by "More than one transformation s...

3 días ago | 0

How to avoid hessian being 0 in fminunc(maximum likelihood estimation)?
Operations in the objective function like this, min(.999999,normcdf(e_inside(t,i)) are technically illegal, since min(a,b) is ...

3 días ago | 0

Question

Automatic numbering and cross-referencing of sections in Live Script
I am investigating the possibility of having automatic section numbering and cross-references in Live Script. Here is an example...

3 días ago | 1 answer | 0

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Combining two matrices with different sizes
M3=zeros(600,2,7); M3(230:598,:,:)=M2; M3(250:2:600,:,:)=M1; %replace M2 with M1 M3(1:2:end,:,:)=0;%odd numbers are zer...

3 días ago | 0

Divide each column by the sum of the column in a matrix
D./sum(D)

3 días ago | 1

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How can i run this code? I get erros "Unable to perform assignment because the size of the left side is 1-by-600 and the size of the right side is 1-by-100."
for j=1:numel(H) for i= 1:numel(T) Tx = T(i); Hx = H(j); P(i,:,j) = fvdWEOSp(Tx,V,Hx); end ...

3 días ago | 0

multi array vectorization problem (reformulated)
runtest(1e2) function runtest(N) A = [ -0.8013 -0.4981; -0.2278 -0.9009]; t = 0:0.01:N; b = [2;3]; [V,d]=eig(A,'v...

3 días ago | 1

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Change the location of points in a 2D meshgrid
location=location+rand(size(location))*0.3+0.2;

4 días ago | 0

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How to formulate the following matrices?
T=makehgtform('translate',[x(i),y(i),0],'zrotate',theta(i)); T=T([1,2,4],[1,2,4])

4 días ago | 1

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bwlabeln 3D connections not a subset of its 2D connections
My guess is that the 4-connected regions are indeed subsets of the 26-connected regions, as you expect. However, in the 26-conne...

4 días ago | 1

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Imposing Constraint in FMINCON optimization problem.
x0 = zeros(1,N_plies); lb = [-ones(1,N_plies)*90 zeros(1,N_plies)]; ub = [ones(1,N_plies)*90 ones(1,N_plies)*t]; Aeq=zeros...

5 días ago | 1

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How to Multiply the following matrices case?
T=rand(3,3,18); D=rand(3,1,18); M=pagemtimes(T,D(:,:)); M(:,logical(eye(18)))=[]; M=reshape(M,3,17,18); whos M

5 días ago | 0

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How to create a matrix?
Do you mean this? [lat,long]=ndgrid(-89.75:89.75,0.25:359.75);

5 días ago | 0

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Merge rows based on conditions in the coulmns

5 días ago | 0

Problems while trying to fit a 4-variable function with lsqcurvefit
voigt_func =@(x,xdata) x(1).*(2.*log(2)./pi.^(3./2)).*(x(2)./x(3).^2)... .*integral(@(t) (exp(-t.^2))./((sqrt(log(2)).*(...

5 días ago | 0

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What is the best way set the search interval used by fminbnd?
Your minimization problem is really a root-finding problem in disguise. It is better to use fzero for such things. As you can se...

6 días ago | 0

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Submitted

Further tools for analyzing objects in N-dimensional images
A collection of tools to supplement bwpropfilt, bwareaopen, and the like.