Matt J

Last seen: Today

7.430 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
exp(-b/x) fit, inf problem when fitting
When x goes to zero, y should go to zero as well since anything power negative infinity is zero. Only if b>=0. g = fittype('ex...

alrededor de 14 horas ago | 0

Answered
accumulating unique indices in array
B = histcounts(A,1:max(A)+1)

alrededor de 15 horas ago | 0

Answered
Sum subarrays of a Matrix.
Using sepblocksun https://www.mathworks.com/matlabcentral/fileexchange/48089-separable-block-wise-operations out=sepblockfun(A...

alrededor de 15 horas ago | 0

Answered
Fast matrix multiplication with diagonal matrices
It doesn't appear to be beneficial to avoid matrix multiplication. N=1e5; W=sprand(N,N,100/N); d=rand(N,1); D=spdiags(d,0,...

1 día ago | 0

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Question

Recover former state of Matlab Editor
I had quite a few files open in the Matlab Editor, but then inadvertently closed the editor window. Is there any way to re-open ...

2 días ago | 1 answer | 0

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answer

Answered
How to calculate reveral summations
T=triu(ones(600)); I=(1:600).' + (1:600); ur=u(:).'; sigma= (T.*ur(I))*ur(1:600).';

2 días ago | 0

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How to calculate reveral summations
Use conv() or xcorr().

2 días ago | 0

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How do I minimize a particular error function with lsqnonlin?
I don't see much that I think can be improved, except perhaps to formulate it so that your errors are differentiable - the lsqno...

2 días ago | 0

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Answered
Get "@" back in a table header (R2017b) when saving
For example, T=table(1,'VariableNames',"name_domain") T.Properties.VariableNames = replace(T.Properties.VariableNames,'_','@...

2 días ago | 0

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How to find splitapply for multiple values
[G, idOcc,idAge] =findgroups(x.occupation,x.Age)

2 días ago | 0

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Answered
Calculation the mean of a portion of a matrix
mean( z(2:end-1,2:end-1) ,'all')

2 días ago | 0

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Answered
Rank one decomposition of a positive semi-definite matrix with inequality trace constraints
Is there any ways I could do the rank one decomposition of matrix X, such that The obvious answer seems to be to test each k to...

3 días ago | 0

Answered
create matrix of integers with specified sum in column and row
You can try to formulate it as an integer program. M=optimvar('M',[4,4],'type','integer'); Constraints.columns=sum(M,1)<=col...

3 días ago | 0

Answered
Finding Upper and Lower Indexes
A = [1;2;3;4;5;8]; B = [3.5;6;2]; c=interp1(A,A,B,'previous'); C=[c(:),c(:)+1]

5 días ago | 1

Answered
Row-normalizing large sparse matrix
The attempt you've posted will only work if vals_W is the same size as sum_vals, which can only occur when there is exactly one ...

6 días ago | 0

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Submitted

Object-oriented tools for fitting conics and quadrics
A tool set for fitting various conics and quadric surfaces, e.g., ellipses, cylinders, spheres, planes, and lines.

7 días ago | 4 downloads |

Answered
Problem with fmincon fval
As Walter suggests, the multiple fvals per iteration are part of finite difference computations needed to evaluate the cost func...

7 días ago | 0

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Finding a row with a certain value and the next nth rows after that
Here's an approach that uses logical indexing only: A=[ 0.9058 0.2785 0.9706 0.4218 0.0357 0.1270 0.5469 ...

7 días ago | 1

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Question

Is there a way to interactively move a plot legend in a Live Editor figure?
In a normal figure window, I can reposition a plot legend by clicking and dragging. Is it possible to do something similar in a ...

8 días ago | 1 answer | 1

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answer

Answered
Best way to move multiple objects with a preallocated matrix of coordinates?
I see movement when I do this, xl=xlim; for b=1:1:nStarts*nCarsPerStart for h=nStarts+1:nStarts:nStarts*(t+1) ...

8 días ago | 0

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Answered
averaging images and subtracting one image from the other
For example, setA=rand(256,256,10); setB=rand(256,256,10); imageA=mean(setA,3); imageB=mean(setB,3); result = imageB-im...

8 días ago | 0

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Answered
Trying to do a curve fitting but having trouble getting it to work.
Do you happen to know why I keep getting the "local minimum possible" Because lsqcurvefit thinks it succeeded in finding a sol...

8 días ago | 0

Answered
Need help creating a variable with different names or a method for saving a variable to different names.
for k=1:K S(k).A(i,j) = readline(s); S(k).B(i,j) = readline(s); S(k).C(i,j) = readline(s); S(k).D(i,j) = readline(s); e...

8 días ago | 0

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Answered
Index in position 1 exceeds array bounds.
Notice! x=rand(5,500); x=x(1:256,1:256);

8 días ago | 0

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I want to combine two plots, one is cone and one is semi-circle
Use hold().

8 días ago | 1

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How to find number of elements using a for loop
for i=1:numel(A), A(i)>2, end

8 días ago | 0

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extracting two specific columns from matrix (Indexing)
x=xxx(:,[1,3])

8 días ago | 0

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Question

Inheriting help documentation from an Abstract base class method
Suppose I have a base class with many subclasses, each of which will override an abstract method in the base class, classdef Ba...

9 días ago | 0 answers | 1

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Answered
Nonlinear fit instead of setting up a non linear equation?
Your problem appears to be a linear fit. I see no non-linear dependence on x or y. You should therefore use lsqlin, if you also ...

10 días ago | 1

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Answered
Would you let me know one of the fastest (or the most efficient) ways to merge data?
final_data = cell2mat(data(:))

10 días ago | 0

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