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J. Alex Lee


Last seen: 1 day ago
67 total contributions since 2016

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Answered
Comparing terms in a character array
If it is truly a "character array" and you want exact matches only, you can use the findstr() command, which will return empty i...

14 days ago | 0

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Answered
Web app system command
To the question: Also, an other question just came to my mind: what's the best practice to store permanent data and access them...

14 days ago | 0

Answered
Getting data from the figure in appdesigner
Here's an example where I used the data cursor's update function itself to collect the coordinates and feed directly into your a...

16 days ago | 1

Answered
reshaping multi dimensional array and central difference method
Based on your example lines, you seem to have the further simplification that your delta x and delta y are uniform (in your exam...

16 days ago | 1

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Answered
Filter a table based on date (Error using tabular/dotParenReference (line 95) Unrecognized row name '01/00/0000'.)
The second way is almost right, but when you use () on testtable, you are extracting a subtable, rather than the datetime array ...

16 days ago | 1

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Answered
Using a image variable from one GUI function to another in AppDesigner
Create a property for your app class to hold the image. You appear to be using appdsigner. In appdesigner's code view, on the l...

18 days ago | 1

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Answered
Plot a curve with its derivatives
As far as I know, matlab's plot function will draw a straight line (linear interpolation) between adjacent points. For your cas...

20 days ago | 0

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Generate matrix of precise length and in ascending order
This seems to work, and is less wasteful RowSum = 10; NCols = 4; NRows = 70000; A = randi(floor((RowSum-2)/(NCols-2)),[NRo...

21 days ago | 0

Answered
How do i create a multi-colour histogram using excel data?
I suspect your yA, yB, yC are column vectors, which you are trying to horizontally concatenate with scalars. You can probably fi...

21 days ago | 0

Answered
How plot a figure like this attached figure?
It's because mesh expects z-data to be actual coordinates in z, but mesh (and surf) will accept a 4th argument for color N = 50...

22 days ago | 0

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Answered
Using trapz doesn't work
F is of size 1x1, not 1x24000

24 days ago | 0

Answered
Painters renderer results in jagged edges
What happens if you set "FaceColor" to "interp" (default is "flat") on the surf object? It fixes the jagge edge for me (2017a or...

26 days ago | 1

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Answered
Solve system of boundary value problem (a singular Jacobian encountered)
If you know the problem is solvable (HW, e.g.,), then singular Jacobian usually means something is wrong with your equations or ...

27 days ago | 0

Answered
determining order of accuracy
This is not a matlab question but a numerical analysis problem. Since someone already generated the results for you, it's a matt...

28 days ago | 0

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Answered
Branching a WindowButtonDown function
If you don't mind using undocumented features, I have had success using the standard axes() object instead of uiaxes(), because ...

29 days ago | 0

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Answered
Proper reading of .txt
Just use readtable()? Looks like every station will have already-aggregated results (hourly vs daily for the same station, same ...

1 month ago | 0

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Answered
ODE solver: how to integrate a system with a vector of parameters?
Are you just looking for solving the ODE as many times as you have different values of V? t = [0 400]; y = [0.004 0 0]; alpha...

1 month ago | 0

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Answered
Limiting mouseclick event to current Axes in App Designer
Cameron's idea of calculating the axes position within the figure position should work, and it is the only way with currently do...

1 month ago | 0

Answered
How to access left bottom pixel in image using (0,0)?
If you just want to translate the unflipped image's row index to be translated into a different index as if you were indexing th...

1 month ago | 0

Answered
How to access left bottom pixel in image using (0,0)?
Since you seem to want to "index" by (0,0), perhaps what you are looking for is assigning real (x,y) coordinates to the image an...

1 month ago | 0

Answered
How to access left bottom pixel in image using (0,0)?
How about if you flip the image? % if the image is in I I = flipud(I)

1 month ago | 0

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how make the plot continuous ?
If I understand correctly, you want the "plot" command to produce a vertical "line" at x=6. To do this, you could duplicate the ...

1 month ago | 0

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Answered
this code is taking a lot of time to run,
If all the files have the same format, I have seen big improvements using detectImportOptions() on the first file re-use those o...

1 month ago | 0

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Answered
Background Color of UIAxes
It is possible to create a regular "axes" within a "uifigure". Can you try that and see if you can accomplish what you need? Thi...

1 month ago | 0

Answered
Installing and running matlab app able to load and process .mat file
If the problem is that the standalone app can't find the file to load in the first place, you need to understand how paths work ...

1 month ago | 0

Answered
calling a function inside an app?
Functions need inputs and outputs, so you will need to define the function su as function out = su(app) out = app.a+app.b ...

2 months ago | 0

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Answered
Solving a second order differential equation
In you function Q5, your 2nd row has a typo, using y instead of y(1)

2 months ago | 0

Answered
How to plot solid and dashed lines?
You need to precede the linestyle you want with the keyword 'LineStyle' plot(x,y,'Color','k','LineStyle','--') so "LineStyle" ...

2 months ago | 1

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Answered
Image segmentation approach to segment lines based on patches
If the shapes you want to segment are parameterizable, and especially if you know how many there are (3 rectangles in this case)...

2 months ago | 0

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Answered
Working with tables that are within a timetable
I would first flatten the table, especially if you will be making many queries. Something like DataCell = cell(height(TT)...

2 months ago | 0

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