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J. Alex Lee


Last seen: 4 days ago
100 total contributions since 2016

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Answered
Reading data from ASCII file
It would have been helpful to know these things in advance (you hinted at the first, but say it explicitly) Data contains multi...

8 days ago | 0

Answered
Surface Fit over image
Here's my first pass thoughts: First steps: Obtain X and Y coordinates of your pixels ensure your pixel values are of type do...

8 days ago | 1

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Question


How to identify ui component classes that other ui components can be children of
I am trying to identify ui components like uipanels, uigridlayouts, uitabs, etc., that may contain other ui components as childr...

20 days ago | 1 answer | 0

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answer

Answered
Plotting points in 3D with mesh
For just visualizing the chosen data in a surface, does this look like what you want? clc; close all; clear; N = 500; X...

29 days ago | 0

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Answered
How can I solve a partial derivative equation if it does not contain a time derivative in MATLAB?
If you mean by "no time variable" that your equation is elliptic in more than 1 independent variable, then unfortunately you'll ...

1 month ago | 0

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Answered
[App Designer] Get the object indentifier that triggered the callback
I think a cleaner way is to pass an identifier with the callback definition: ASpinner.ValueChangedFcn = @(evnt)app.VChanged(evn...

1 month ago | 0

Answered
Plotting a graphic output of an external function in APPDESIGNER, more specifically the uiaxes
If there is no way to activate a uiaxes programmatically, you can try to create a regular axes in app designer in the startupfcn...

1 month ago | 0

Answered
Roots of a two variables equation involving a numerical integration
Assuming x and y are scalars and there is a solution, use fsolve, not an optimization algorithm. You'll need initial guesses. Th...

1 month ago | 1

Answered
Accessing an element of an array using an array as its index.
Interesting...I guess your question title should be edited to "use array as subscripts into multidimensional array". I dug into ...

2 months ago | 0

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Answered
Struct to numeric variable
At the risk of having misunderstood: new_var = [structname.fieldname] This would work if you structname is a structure array 4...

2 months ago | 0

Answered
How can I specify the way components resize automatically in App Designer?
"uigridlayout" was introduced in 2018b, which may be helpful...It allows pretty sophisticated layouts, although it still seems b...

2 months ago | 1

Answered
How to add the value of the 3 highest elements automatically from a vector?
like this? [~,idx] = maxk(y,3) y(idx) = y(idx) + sx Are x1 and x2 irrelevant to your question?

2 months ago | 0

Answered
How to map a vector to a colourmap ?
A brute force way would be to interpolate...not sure if there's a better way x = % ... data vector indices = 0:255; xref = ...

2 months ago | 1

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Answered
Making a square figure with pcolor
Your coordinate grid matrices x and y are not "aligned" with the axes. You can see this if you just do plot3(x,y,zeros(size(x)...

2 months ago | 0

Answered
Getting Cell location of checkboxes on selection (UITable)
Is it as simple as defining a CellEditCallback?

2 months ago | 0

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Answered
Is there an automatic way to find the centre of this circularly-symmetric pattern?
This would be not at all efficient and maybe not robust, but you could pose a minimization problem: Find the coordinates (Xc,Yc...

2 months ago | 0

Answered
How can I create binEdges?
It looks like your problem is not with binning, but the fact that you have NaN's in your data. By the way if you have 2014b or ...

2 months ago | 0

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Answered
Extracting particular x and y data points from a figure
Thinking in terms of graphs is useful but only takes you so far. The point is how to think about the data and/or functions under...

2 months ago | 0

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Answered
Help in implementing ode45 in app designer
Static methods don't assume that the app is passed as the first argument, so remove "app" from the arg list methods (Static) ...

3 months ago | 0

Answered
Validate and get exact number of characters using the regular expression
Try out_str = regexp(str, '[A-Z]+-[0-9]{2}$', 'match');

3 months ago | 1

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Answered
How to initialize a new matrix of the same type as an existing variable?
I am not sure if this works for symbolic type, but you can initialize an array of arbitrary type by specifying the "last" elemen...

3 months ago | 0

Answered
How to remove outliers based on datetime
What if you ran statistics on real or integer representations of datetime, using datenum() or something?

3 months ago | 0

Answered
lsqcurvefit initial point is always a local minimum, relative first-order optimality is always = 0
I think you have a typo here: F = @(v,cur_data_wave_x) amplitude*(offset + cos(v0(1)*(cur_data_wave_x) + v0(2))); should rathe...

3 months ago | 0

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Answered
Applying a for loop to every column in a vector
Agree with KSSV, avoid naming as "max", but in this case it is not causing your problem. Your problem is that "index" should no...

3 months ago | 0

Answered
How to choose 5 random rows from an array of 8 rows for 10 times and save the 10 results
if order doesn't matter (6,4,8,7,2 is the same as 4,6,8,7,2) doc nchoosek if order does matter (6,4,8,7,2 is different from 4,...

3 months ago | 1

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Answered
solving a second spatial derivative using ode45
This comment is incorrect: % Create a two element vector that holds the derivative equations of u and % v % U(1) is u and U(2...

3 months ago | 0

Answered
How to save file on chosen path in app designer?
can you just simplify and use uiputfile()?

3 months ago | 0

Answered
Implicit Boundary Value Problem
Ok, so looks like what you are after is solving a DAE that has BCs at more than one boundary. Docs say it is ode15s and ode23t ...

3 months ago | 0

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Answered
Select mxm matrix from mxn matrix and solve systems of linear equations
Does this help with first problem: https://www.mathworks.com/help/matlab/ref/nchoosek.html Second problem, maybe make tolerance...

3 months ago | 1

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Answered
Reduce time execution in a real time serial data reading
If instead of a loop, you use a timer (https://www.mathworks.com/help/matlab/matlab_prog/use-a-matlab-timer-object.html), you mi...

3 months ago | 0

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