J. Alex Lee
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Content Feed
Implementing Crank Nicholson in spherical setting
I believe this should be the right formulation for CN (taking a few liberties interpreting your problem). If you want speed, pr...
2 months ago | 0
Implementing Crank Nicholson in spherical setting
For one thing, your boundary conditions (as developed on your pdf) don't look right. At r=0, you can just directly use Eq 8 LHS...
2 months ago | 0
Question
Built in look-up style interpolation of timetables for non-numeric data?
Is there no built-in function similar to interp1 for numeric data, that can operate on timetables with arbitrary data types? So...
2 months ago | 1 answer | 0
1
answerFor loop to carry value down depending on another matrix value
In your example, there is a "delay" by 1 row when your switch from 0 to -1 occurs, so the following answer is not exactly produc...
3 months ago | 0
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There used to be a function RefineMesh in Matlab used in solving ODE's, but it is now used for PDE's and isn't the same function. Is there a new function for the old purpose?
The workflow above only re-evaluates the "static" solution of ode45 at more data points by an interpolation scheme consistent wi...
6 months ago | 0
Is there a way to measure interletter spacing for Fixed Width font in MATLAB?
I have no idea what you mean by "visual angle per font size", but I know of one way: lbl = uicontrol("Style","text","String","...
7 months ago | 0
Functional programming construct to expand cell array into arguments for other functions without using an intermediate variable in the (user) code?
I am still not sure why you can't just have your generalized comparator function saved as a function somewhere on your path so y...
9 months ago | 1
How to integrate uidatepicker command with GUI interface?
Details are thin here...but it sounds like you need to first specify the parent graphics object that you want your uidatepicker ...
9 months ago | 0
How to solve exponential equation to find unknown constants
data = readtable("Book1.xlsx"); Alternatively, based on my reparameterization above you can as a first pass say everything afte...
9 months ago | 0
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How to solve exponential equation to find unknown constants
Do you have an intuition of what the graph of looks like? Hint: it looks like your plot, scaled and shifted roughly only in the...
9 months ago | 0
Print vectorized graphic of patches without edges
I now believe it is because you are technically plotting 3D patches (telling Matlab there's a z-coordinate, even if they are all...
9 months ago | 1
Calculations of Angle between two points
If you have the list of 3D coordinates rng(1) % control random generator NPoints = 5 vertices = rand(NPoints,3) You can defi...
9 months ago | 0
How to symbolically integrate f(T) = exp (E/(8.314*T) through integration by parts or with trapezoidal method?
The application still is unclear to me... If you just want numerical integration, look at the function "integral", as implement...
9 months ago | 0
Remove zoom from axes
This should be a good entrypoint: https://www.mathworks.com/help/matlab/ref/disabledefaultinteractivity.html https://www.mathw...
10 months ago | 0
Can I pass arguments to a @callbackFcn?
configureCallback(s,"terminator",@(src,evnt)readSerialData(src,evnt,operation mode)) So the first parentheses specify the inter...
10 months ago | 1
| accepted
I am trying to find the exact distance of a curvy line.
Assuming that the boundary points are ordered well (adjacently), then you can calculate the cummulative square distance between ...
10 months ago | 0
Take only some values from one array
you can't compare arrays of different lengths. a straightforward but cumbersome way is to cycle through each of your t1 and find...
10 months ago | 0
MATLAB GUIDE to App migration question
Apparently it should work: https://www.mathworks.com/help/matlab/creating_guis/compatibility-between-different-releases-of-app-...
11 months ago | 0
| accepted
How to Save new data to existing structure data in a for loop without having to save the complete Matlab file from Zero?
I would consider using a database, a lightweight solution could be sqlite. I use the third party mksqlite for this purpose and i...
11 months ago | 0
using varfun on a timetable with subscripts?
first of all, your operation looks like a "diff", no subscripts (for rows, i.e., timestamps) necessary second, you will be defi...
11 months ago | 0
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How can I quickly obtain the inverse of a square sparse matrix?
potentially, if you have more information about the properties of A, you can specify them in a call to linsolve https://www.mat...
11 months ago | 0
| accepted
3D/2D matrix multiplication without using a loop
I found this: pagemtimes() s = rand(5,5); x = rand(5,8,100000); tic y = pagemtimes(s,x); toc tic z = nan(size(x)); for...
11 months ago | 0
How to operate properly with multidimensional matrices and cells.
You might be looking for squeeze()? l=0; % preallocate C = cell(3,3,3); M = nan(3,3,3); % construct 3D cell and matrix ...
11 months ago | 1
How to solve a system of second order nonlinear differential equations with boundary conditions
This is a boundary value problem, so probably the most straightforward way is to use bvp4c or bvp5c if you want to solve numeric...
11 months ago | 1
| accepted
Backward and Central Difference
I guess the answer depends what you want to do with those finite difference approximations. If you want to use it in an algorith...
11 months ago | 0
| accepted
Save class object as struct
Look at this too: https://www.mathworks.com/help/matlab/matlab_oop/flexible-saveobj-and-loadobj-pattern.html I think it means w...
11 months ago | 1
| accepted
Can't get string to datetime conversion to work
str = '2019-05-17T19:36:00'; fmt = 'yyyy-MM-dd HH:mm:ss'; b = strrep(str,'T',' '); disp(b); timestamp = datetime(b,'Inpu...
11 months ago | 0
Auto Refresh in app designer.
in general for "auto refresh" you can use the timer object to schedule recurrent execution - disclaimer i have only played with ...
12 months ago | 0
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Using Hessian for least squares problem
Now that the actual question is clarified as a coding question and not a math question, it seems these should help: https://www...
12 months ago | 0
| accepted
Select rows in a given table according to 3 criteria
This is small enough you could generate the full list of combinations % generate all combinations alltriplets = nchoosek(1:7,3...
12 months ago | 0
| accepted
