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Matt J


6.033 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

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Answered
Rasterize a triangle in 3-D space.
One way is to use vert2lcon, https://www.mathworks.com/matlabcentral/fileexchange/30892-analyze-n-dimensional-polyhedra-in-term...

3 dagen ago | 0

Answered
How to find the x and y coordinates corresponding to a given value of f(x,y)?
maxval=max(f(:)); [xmax,ymax]=find(f==maxval);

3 dagen ago | 1

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Answered
Why do results of fft() on a matrix differ from fft() on one row as a vector?
The same dicrepancy exists with most Matlab functions that do operations along rows or columns. Here is the same test replacing ...

3 dagen ago | 1

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Answered
why the script show wrong output can you help me?
tplot=[0:0.01:2*pi]; x=double(subs(pos,tplot)); y=double(subs(v,tplot)); z=double(subs(a,tplot)); p=plot3(x,y,z);

3 dagen ago | 0

Answered
From a set of curves, how to find the one that the "most similar" to the reference curve?
The code below uses fminspleas https://www.mathworks.com/matlabcentral/fileexchange/10093-fminspleas to do a simple 1D registr...

4 dagen ago | 0

Answered
Sparse gpuArray accumulation in for-loop
I would guess that your Kernel matrix is becoming less and less sparse as you accumulate until its memory consumption is growing...

4 dagen ago | 0

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Answered
Optimization with loops Error in optim.problemdef.OptimizationProblem/solve
I believe it will probably involve multiplication by some upper triangle matrices of 1 with some other operations but I cannot w...

4 dagen ago | 0

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Answered
Find the points on circumference of a circle
Okay Considering 5 pixels + or - for the inaccuracy to find all the x,y, points on the circumference; how can I find even those....

4 dagen ago | 0

Answered
Matlab code to split an image into a square grid of square blocks
This uses mat2tiles (Download) A=mat2tiles( imread('cameraman.tif'), [32,32]); [m,n]=size(A); B=cell2mat(A(randperm(...

4 dagen ago | 0

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Answered
Find matching points from two coordinate systems
If the shear component of the deformation isn't too strong, the matchpoints function defined below might work. It will sort the ...

6 dagen ago | 0

Answered
Find cycles in an undirected graph
Because this sounds like a generally useful thing, I cooked up the attached polyregions class to do the partitioning that you de...

6 dagen ago | 1

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Answered
Function handle for combinations of calculations
One way: N=5; [G{1:N}]=ndgrid([-1,1]); G=reshape(cat(N+1,G{:}) , [],N); and now the combinations are given by ...

6 dagen ago | 0

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Answered
I need help with this MATLAB question
I know how to get user input but how do i get it through a pop up box? One option is inputdlg, https://www.mathworks.com/help...

6 dagen ago | 1

Answered
How do I reorder unequal columns in a field
yourStruct.Vs=permute(yourStruct.Vs,[2,1,3]);

7 dagen ago | 0

Answered
How to use polyfit for a table of values
That would occur if mpg or horsepower contain NaNs. You should remove them.

7 dagen ago | 0

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Answered
imquantize code is required
elseif(T1<I(x,y) | I(x,y)<=T2)

7 dagen ago | 0

Answered
Index exceeds the number of array elements (5)
for i=1:n-1

7 dagen ago | 0

Answered
Using maximum of optimisation variable as an upper bound for another variable
Solve N different sub-problems for j=1:N prob.Constraint.TotalCost = sum(x)=CostPerkW*x(j); prob.Constraint.Max =...

7 dagen ago | 0

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Answered
Error using griddedInterpolant Grid coordinates must be of the same type, single or double.
You should convert all your variables to double floats.

8 dagen ago | 0

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Answered
how to solve Error using .' Transpose on ND array is not defined. Use PERMUTE instead. Error in interp2 (line 122) V = V.';?
Because precip is not a 2D array, interp2 is the wrong tool. One alternative: F=griddedInterpolant({lat,lon,t},precip); newp...

8 dagen ago | 0

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Answered
calculate rotation of an object using three markers connected to an object
You can use this FEX file to calculate the rotation of a set of points, https://www.mathworks.com/matlabcentral/fileexchange/26...

9 dagen ago | 1

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Answered
Solving a system of nonlinear equations with unorganized unknowns?
If you use lsqnonlin instead of fsolve, you can set a vector of upper and lower bounds ub and lb on the solution. Just set ub(i)...

10 dagen ago | 0

Answered
How can i write optimal control objective with fmincon?
Same as any objective... Knowns=[lambda1,lambda2]; Jfun=@(Unknowns) objective(Unknowns,Knowns); fmincon(Jfun , InitialGue...

10 dagen ago | 0

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Answered
linprog says 'no feasible solution found' even though there is one
Here's another way you could solve it: if rank(xAeq)==num_edges weightsOptimal=xAeq\xbeq; ...

10 dagen ago | 0

Answered
What starting point to choose so fsolve always returns a solution when any exists?
Can I choose such a starting point so that fsolve will always find a solution if there is any? Maybe the center of the circle/sp...

10 dagen ago | 1

Answered
How to determine unknown value from an equation
It's a cubic polynomial, so you can use roots().

10 dagen ago | 1

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Answered
linprog says 'no feasible solution found' even though there is one
Basically, the problem is that your equality constraint matrix xAeq is full rank: >> rank(xAeq) ans = 8 >> cond(x...

11 dagen ago | 1

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Answered
Which is the best optimization method for optimizing over probability mass functions?
fmincon is most appropriate because your objective is non-linear and non-quadratic. However, your constraints are all linear, so...

11 dagen ago | 0

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Answered
Optimization of 9 unknown with 9 nonlinear constraints by fmincom
It seems highly likely that your problem is over-constrained. With 9 equality constraints and 9 unknowns, you may have enough eq...

11 dagen ago | 1

Answered
How to interpolate ‘z’ for one value of ‘x’ but multiple values of y?
If an interpolation result is giving you NaN, it normally means you are interpolating at a location which is outside the area co...

12 dagen ago | 0

| accepted

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