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J. Alex Lee


Last seen: 1 dag ago
163 total contributions since 2016

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Answered
How to speed up the simulation time of a big system of ODEs?
don't use syms

7 dagen ago | 0

Answered
Indexing arrays of binned data
From what I can gather, it hsould be possible to reorganize your experimental data into a Nx6 matrix called Data, where N is the...

8 dagen ago | 0

Answered
regression line in quadratic form
[edited] Alternatively, just create a new variable to hold an already sorted "model" experience N = 200; % choose an arbitrary ...

9 dagen ago | 1

Answered
Reading large excel file using "read" command takes ~5 minutes, is this expected performance?
Try manually creating the import options with spreadsheetimportoptions().

12 dagen ago | 0

Answered
How to use datetime as a condition in foor loop?
i believe you can, you just have coded it as a comparison of a datetime to a string. A(i,1) == datetime(2019,1,dd)

13 dagen ago | 0

Answered
How to fill the gaps in a patch plot through adaptive interpolation
If you reduce your current patches into single (x,y) coordinates, e.g., center of mass, then you can triangulate/find the vorono...

14 dagen ago | 0

Answered
How to fill the gaps in a patch plot through adaptive interpolation
You could add in "corners" where your red curves intersect the y-axes as new (x,y) coordinates, then do a convexhull on them. Th...

15 dagen ago | 0

Answered
Preallocation with object structures
I don't think you are understanding "preallocation" correctly based on your last example...matlab is [probably] asking you to "r...

15 dagen ago | 1

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Answered
Creation of a mask on RGB image
Instead of multiplying pixels in the mask by a constant value, you can mulitply all pixels by an "image" of the saturation multi...

15 dagen ago | 1

| accepted

Answered
Reading data with multiple headers
other experts on the forum for text parsing may have better ways, but you can scan through line by line and apply regular expres...

17 dagen ago | 0

Answered
How can I get points coordinate on an axes made in GUI?
It sounds like the click is being "intercepted" by the object that you drew on the axes (please don't use the word "figure", bec...

19 dagen ago | 0

Answered
Matlabでのバーチャルな写真の撮影について
ax.DataAspectRatio = [1,1,1] also ax.Projection = "perspective" and various other "camera"-related properties like: cameravie...

19 dagen ago | 0

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Answered
How an I manipulate top and bottom x axes individually?
Actually, dpb's suggestion of 2 axes should work as long as you don't turn "box on", and you may need to sync their positions if...

19 dagen ago | 0

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Solved


Convert a temperature reading from Celsius to an unknown scale
Two of the most famous temperature scales are the Celsius and the Fahrenheit scale. In reality, however, there are so many other...

20 dagen ago

Solved


Length of a short side
Calculate the length of the short side, a, of a right-angled triangle with hypotenuse of length c, and other short side of lengt...

20 dagen ago

Answered
Logical Indexing instead of loops in 3D-Matrices
What is the purpose of vectorization? Is it for imagined speed gains, or just an "in principle" question? Bruno's answer is fas...

21 dagen ago | 2

Answered
How can I insert a square root in y-axis of curve ?
You can use latex ylabel('$$\theta \quad \left(10^{-3} \mathrm{C/m} \sqrt{\mathrm{kg}}\right)$$','Interpreter','latex') also ...

22 dagen ago | 1

| accepted

Answered
Multiple linear regression coefficient calculation
Assuming your data are in rows (y is a column vector), isn't that just X=[ones(size(x1)),x1,x3,x3] see https://www.mathworks...

25 dagen ago | 0

Answered
How to vectorize an equation involving pair-wise distance computation, to improve the speed of computation?
I think you should be able to loop only once over the reference point , then take then compute difference vectorially. Also, in...

28 dagen ago | 1

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Answered
How can I draw the following blue color tone intensity figure using the Newtons Raphson basin of attraction code?
Organize your "list" of initial guesses (x,y) as a meshgrid [X,Y] = meshgrid(x,y) Then easier to loop through the "unwrapped" ...

28 dagen ago | 0

Answered
how to merge multiple timetable
If the tables have the same columns, you should be able to simply vertically concatenate them and sort t0 = sortrows(vertcat(t1...

28 dagen ago | 1

Answered
Plotting 3D graph with ODEs
If your ODE result "population(t)" a scalar value, then yes, you can use surf() if your [A,B] is defined using meshgrid.

28 dagen ago | 0

Answered
Indexing concurrent array elements and incrementing
First you could use "reshape" to create a 2D array whose rows corresponds to a record, then slice up the 2D array into however m...

29 dagen ago | 0

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Answered
UITable in app designer-Matlab
I think this works if you have a recent version of matlab, you can place the uitable inside a uigridlayout, and set the "cell" h...

29 dagen ago | 1

Answered
Counting occurrence of keys and values for Containers.Map in another Containers.Map
Just considering the keys, you can use ismember (though I'm not sure why there's a limitation that cells must be cell arrays of ...

ongeveer een maand ago | 0

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Answered
How do I plot logarithmic error?
In log space, spacing is multiplicative, not additive, so you want to express your top and bottom curves as multiples of your ba...

ongeveer een maand ago | 0

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Answered
How do I plot logarithmic error?
use the log10() function? The question isn't super clear...

ongeveer een maand ago | 0

Answered
Convert numerical equations to latex
Assuming the results will always be integers, here's a simple way %==== Numerical Values (Unrounded) ============== a = 128387...

ongeveer een maand ago | 0

Answered
find indices of each first repeated elements in the array (full of repeated values)
It's too early for me to attempt to understand your 2nd problem, but for the first problem try using "diff" indexB0 = [1,1+find...

ongeveer een maand ago | 0

| accepted

Answered
Fitting 2D Gaussian to histogram
If you only need the center, you can just take the mean in each direction x = mean(A) y = mean(B)

ongeveer een maand ago | 0

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