# Matt J

Last seen: Today Con actividad desde 2009

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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.

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Why are the components of the two eigenvectors not continuous and smooth, when the underlying data is continuous and smooth?
Note that eigenvectors are not generally continuous functions of the matrix entries, as shown in this old example from J.W. Give...

alrededor de 19 horas hace | 1

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How to speed up my code (computing jacobian)
You can use equationsToMatrix to obtain the Jacobian. Depending on what you are doing, you might then convert the matrix to doub...

3 días hace | 0

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How to distinguish pressing cancel vs entering an empty string in inputdlg?
However, this does not distinguish between meaningfully enterring an empty string and pressing cancel/x. It should. Hitting ok...

4 días hace | 0

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fminunc limit step size
No, there is no way to limit the stepsize, but you shouldn't be using a random initial point. That is never a good idea.

4 días hace | 0

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How do I remove outliers in data so that vectors are of the same length for plotting?

7 días hace | 1

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inv(A)*B*inv(A) or A\B/A, which is more accurate for a full rank A and half rank B
I tried both inv(A)*B*inv(A) or A\B/A, resulting in very different results for a gradient descent algorithm. From this, it woul...

7 días hace | 0

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Accessing data from same variables within different tables in a structural array
fcn=@(p) interp1( p.data.TimeCooling , p .data.TempCore, timepoints(:)); TempCore_Lookups= cell2mat(arrayfun(fcn,p,'un...

8 días hace | 0

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One function is greater than other
Let us reorganize the inequality as, Since log(z)>0 in the given domain of z, this implies which in turn implies that...

8 días hace | 0

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Finding accurate inverse of binary circulant matrix
We don't know what it is that you consider improper about the results of inv(). The test below indicates to me that everything i...

8 días hace | 0

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Proving one function is greater than other?
Make the change of variables and rearrange the inequality as, Since is a convex function on such that >0 and , it read...

9 días hace | 0

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Function to trainNetwork returns an unexpected error
Your X_train and y_train data were in some weird format that trainNetwork cannot recognize. Try this instead, Xdata = num2cell(...

10 días hace | 0

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orthogonal projection of 3D nodes onto a 2D plane
You should post questions about a FEX file on the submission's FEX Discussion forum, since only its author is likely to have the...

10 días hace | 0

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Surf on a cylinder
% Step 1: Create the heatmap data % Example heatmap data heatmapData = peaks(50); % Replace this with your actual heatmap dat...

10 días hace | 0

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create a 3D smoothing with csaps (or similar)
load curve_1 cc = curve_1; %or curve_2 x = cc(:,1); y = cc(:,2); z = cc(:,3); t=linspace(0,1,height(cc)); tu=linspace(0...

11 días hace | 1

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How to train a vector multiple-input multiple-output network
You have only entered one InputDataFormat. The error message is telling you that you need two of them, e.g., options = training...

12 días hace | 0

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Create different interpolation steps in a column
newy=[1:10,12:2:30, 50:50:500]; newdata=interp1(y,data,newy);

14 días hace | 0

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lambda in fmincon Interior-Point Algorithm with Analytic Hessian
How come it is an input to the function hessinterior? Because both x and lambda are computed iteratively. The solver therefore...

14 días hace | 0

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Finding the minimum distance between two matrices
See pdist2.

14 días hace | 1

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Fitting a function with constraints
You can use a custom model for each case: ascending: The minimum y-value must be at the first x-value g = fittype( @(a, t, c, ...

14 días hace | 0

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Solve ill-conditioned linear systems
Ill-conditioning is a property of the problem, not the method of solution. You cannot overcome it with any particular choice of ...

15 días hace | 0

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Calculations for Each Table in a Cell
for i =1:numel(CoPyData) Trial = CoPyData{i}; CoPv_y = diff(Trial.Displacement)./diff(Trial.Time); CoPv = [...

15 días hace | 0

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Change dimension of a structure
s.Height=3600; s.Width=3601;

15 días hace | 0

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find the inflection point of a curve 3D (set of nodes) in matlab
You can use csaps to fit a smoothing spline to the points and then fnder to differentiate the curve and observe curvature change...

15 días hace | 0

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How to put 3D array data into mesh grid and find grid cell index of a cube enclosing a given point?
It would be much simpler and more efficient to skip the meshgrid altogether and use discretize. i=discretize(px,x); j=discret...

15 días hace | 0

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How to fit polygon to irregular set of points with only vertical and horizontal edges?
You will need to use a Traveling Salesman Problem solver to sort the vertices. There are a number of them on the File Exchange. ...

15 días hace | 1

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Complex value computed by model function, fitting cannot continue. Try using or tightening upper and lower bounds on coefficients.

15 días hace | 0

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How to find norm of a 3 X 1 matrix if it contains components in parametric form?
syms t coupler_parametric=[5163136522924301/2251799813685248,... 2^(1/2)/2 - (8*t)/(t^2 + 1), - (4*(t^2 - 1))/(t^2 + 1) - ...

16 días hace | 1

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wrong type variable in uitable
"Unrecognized property 'VariableTypes' for class 'matlab.ui.control.Table'." Indeed, there is no such property. Why did you put...

17 días hace | 0

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create a 3D average plan (or normal) from two 3D plans (or normals)
There is no universally recognized concept of an "average plane". One definition you could adopt is the plane obtained by fittin...

17 días hace | 0

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polynomial multiplication not accurate, using conv() vs symbolic
To avoid the numerical instabilities of high order polynomials, don't work with the coefficients of D4_poly^2. Just evaluate D4_...

18 días hace | 0