Community Profile

# J. Alex Lee

##### Last seen: Today
89 total contributions since 2016

View details...

Contributions in
View by

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?

8 dagar ago | 0

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 = ...

12 dagar ago | 1

| accepted

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)...

19 dagar ago | 0

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

22 dagar ago | 0

| accepted

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...

24 dagar ago | 0

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 ...

24 dagar ago | 0

| accepted

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...

24 dagar ago | 0

| accepted

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) ...

27 dagar ago | 0

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

28 dagar ago | 1

| accepted

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...

30 dagar ago | 0

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

ungefär en månad ago | 0

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...

ungefär en månad ago | 0

| accepted

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...

ungefär en månad ago | 0

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,...

ungefär en månad ago | 1

| accepted

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...

ungefär en månad ago | 0

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

ungefär en månad ago | 0

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 ...

ungefär en månad ago | 0

| accepted

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...

ungefär en månad ago | 1

| accepted

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...

ungefär en månad ago | 0

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,...

ungefär en månad ago | 0

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 ...

ungefär en månad ago | 0

| accepted

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...

ungefär en månad ago | 1

| accepted

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...

ungefär 2 månader ago | 0

| accepted

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...

ungefär 2 månader ago | 0

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...

ungefär 2 månader ago | 1

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...

ungefär 2 månader ago | 1

| accepted

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 ...

ungefär 2 månader ago | 1

| accepted

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...

ungefär 2 månader ago | 1

| accepted