Community Profile

photo

J. Alex Lee


Last seen: Today
73 total contributions since 2016

J. Alex Lee's Badges

  • Revival Level 1
  • Knowledgeable Level 3
  • First Review
  • Solver
  • Thankful Level 1
  • First Answer

View details...

Contributions in
View by

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 ...

17 hours ago | 0

| accepted

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...

1 day ago | 0

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...

1 day ago | 0

Answered
how to generate text file from generated output
fprintf() accepts as 1st argument a file identifier for a file opened with fopen(). fid = fopen("somefile","w") fprintf(fid,...

1 day ago | 0

Answered
App designer: Enable mouse scroll to change value on slider
Take a look at the UIFigure's following properties: WindowScrollWheelFcn WindowKeyPressFcn WindowKeyReleasedFcn If you need ...

3 days ago | 0

| accepted

Answered
Trying to identify directions of overlapping lines in images, at my wit's end
Have you looked into radon transforms? You might get some "signal" at the 45 and 135 directions for the right image... If these...

3 days ago | 1

| accepted

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...

18 days ago | 0

| accepted

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...

18 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...

20 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...

20 days ago | 1

| accepted

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 ...

20 days ago | 1

| accepted

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...

22 days ago | 1

| accepted

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...

24 days ago | 0

Answered
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...

25 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...

25 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...

26 days ago | 0

| accepted

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

28 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...

1 month ago | 1

| accepted

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 ...

1 month 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...

1 month ago | 0

| accepted

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 ...

1 month ago | 0

| accepted

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

| accepted

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

| accepted

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

Answered
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

| accepted

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

| accepted

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...

2 months ago | 0

Load more