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Walter Roberson


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48,050 total contributions since 2011

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location.

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Answered
Calling a function multiple times in a for loop.
psi(k) = test_M(rmv(k));

1 hour ago | 0

| accepted

Answered
why my licence will expire
We do not have enough information about your license. Individual licenses do not expire for Home licenses or most Student licen...

1 hour ago | 0

Answered
loglog plots don't always use log scale
The y axis *is* on log scale. Compare the distance between the bottom (1.0) and the tick above it (1.05) to the distance between...

2 hours ago | 0

Answered
Randomisation of matrix for load forecasting
No, not in itself. You could use p as column indices, but when you submit all of the data together then it does not care what ot...

3 hours ago | 0

Answered
Unrecognized function or variable 'x'. Error (line 65)
num2str returns a character vector. You are trying to add and subtract character vectors, which MATLAB considers the same thing ...

4 hours ago | 0

Answered
Trouble keeping three decimal places in my output
There is limited control over the way that table objects display values. table objects respond to the active setting for format,...

4 hours ago | 0

Answered
Index exceeds the number of array elements (4)
dy_v= [1 NaN NaN -0.67]; % The slopes/clamps at the end 4 entries. x_v=[1 2 5 6 7 8 10 13 17]; % The corresponding x va...

7 hours ago | 0

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Answered
macOS disk space after Update to R2020b
You should be looking at: ~/Documents/MATLAB/Examples %examples you loaded at some point and might not need ~/Docum...

7 hours ago | 0

Answered
Fitting Data from a matrix to polynomial
XY = [0.0 180.48242260204557 1.0472413857496277 -2.8019794514594967E-14 1.9636664333660168 -37.722506925880054 2.9199...

8 hours ago | 0

Answered
I need help with my code
c1 = ult_trid(m,b); In your main function, that is the first time you mention c1, and it is an output from ult_trid . function...

8 hours ago | 0

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Answered
I got a matrix dimensions error while plotting a pressure field
p = 101325-1/2*1.225*(900+(90/pi)*(X1./(X1.^2+Y1.^2))+9./(4*pi^2*(X1.^2+Y1.^2)));

9 hours ago | 0

Answered
Name must contain a single string
See https://www.mathworks.com/matlabcentral/answers/349442-how-to-solve-the-stopfcn-error-when-the-cause-is-vectors-must-be-the-...

9 hours ago | 0

Answered
Reversible matrix in matlab
You need to take that code for irr_mat and store it in file irr_mat.m

20 hours ago | 1

Answered
The number of rows in A must be the same as the number of elements of b.
MATLAB function calls use positional parameters, not named parameters. The second parameter you are passing, u0, is getting rece...

20 hours ago | 1

Answered
Can I schedule a job in Matlab online
You can use timer objects. Note that MATLAB Online will time out if you do not interact with the session from time to time. S...

21 hours ago | 0

Answered
How can I randomly shuffle columns in my matrix
randperm() the number of columns and use the result as the column indices A(:, randperm(size(A, 2)))

21 hours ago | 1

Answered
Can I use system composer with Matlab home license?
No, System Composer is not available for Home licenses.

21 hours ago | 0

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Answered
Matlab doesn't do the complicated integration
int is for closed form integration to get an indefinitely precise solution. You cannot justify getting an indefinitely precise s...

22 hours ago | 0

Answered
how to count the number of terms in syms
feval(symengine, 'nops', A) In newer releases you can numel(children(A)) but that is several years after your version

22 hours ago | 1

Answered
can i convert matlab simulink model into matlab code?
No. There are no tools to convert Simulink to MATLAB. There are tools to convert Simulink to C or C++. Most Simulink blocks h...

23 hours ago | 0

Answered
What code is it?
That is not code. That is a .mat file created on a Windows system about a week ago. Possibly someone accidentally did a save...

24 hours ago | 0

Answered
How can I stop the pushbutton of guide being pressed until the callback function is executed completely ?
Set the Interruptible property to off. This will, though, prevent even timer interrupts if I understand correctly. The facili...

1 day ago | 0

Answered
Can I download multiple versions of MATLAB with campus license?
Campus licenses are Educational licenses (not Student licenses.) The technical contact for the license has the option of restric...

1 day ago | 0

Answered
is used PixelLabelDataStore?
FileExtensions is from a later release than you are using. Your release cannot used nii files with pixel label store, if I re...

1 day ago | 0

Answered
Infinite symsum returns symbolic number.
I do not know why that happens, but do this for a workaround: syms n x=0.5; y=1.5; f = (400/sinh(2*n*pi))*(((n*pi)*(1-(((-...

1 day ago | 0

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Answered
Repeating a sequence of code multiple times in a for loop with random intervals in between
rec=@(x) (x)>=0.75; for counter = 1 : 150 j = (0 : 0.01 : 29); k = sin(j); f = rec(k); [a,b]=find(f~=0); ...

1 day ago | 0

Answered
Using matlab's spmd to compute simple triple integral is giving me incorrect solution, any thoughts on what I am doing wrong?
You integrate the first section of x with the first section of y and the first section of z, and the second section of x with th...

1 day ago | 0

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Answered
Make a matrix with matching numbers per column from a bigger one
mask = A(:,1) == 2011 & A(:,5) == 101; B = A(mask,:);

1 day ago | 1

| accepted

Answered
Generate a 100000x100000 matrix that takes less time and memory
a=zeros(ni,ni,'uint8'); You are already using only one byte per entry. If you were to create logic that packed 8 adjacent ent...

1 day ago | 1

Answered
Start an external program (.exe) inside a matlab window
External processes always run as a separate window. However for non-graphic processes, you can control the standard output and s...

1 day ago | 0

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