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Walter Roberson


42,634 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
Index exceeds matrix dimensions. error
Your code is using the bus numbers, up to 101, as indices into arrays that as sized according to the number of busses. In places...

4 hours ago | 0

Answered
Get correct positions on gui to draw lines between pushbuttons GUIDE
The Position of a uicontrol is never axes data coordinates such as is needed to draw on the image. axes ah = axes('unit', 'no...

5 hours ago | 0

Answered
Does anyone now the coding for de-quantization?
Take all oc of your numbers and quantize them each to be 0 or 1. Now take all of the bits that result and put them together in s...

13 hours ago | 0

Answered
Error using integral function
u = double(sol_u); k = double(sol_k);

13 hours ago | 0

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Answered
Error using Eigenfaces Too many output arguments. Error in ONL_REC (line 37) testimage=Eigenfaces*E;
m is some unknown variable loaded from your latest.mat or outputttt.mat . We have no idea what size it is. You create a variable...

14 hours ago | 1

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Answered
Looping through 3d
dayrate = reshape(rate, [41 40 24 31]); for ind_day = 1:31 for ind_hr = 0:23 filename = fullfile(folder, sprintf(...

1 day ago | 0

Answered
How to import big data CSV files
These days, often the most convenient way is to use detectImportOptions, and set the SelectedVariableNames property of that to c...

1 day ago | 1

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Answered
Pass a function as argument Matlab6.1
Looking at an old document https://web.stanford.edu/class/ee254/software/using_ml.pdf it appears that in R12, function handles e...

1 day ago | 0

Answered
Mean Filter is Linear or non_Linear filter?
Mean filtering is always over a sliding window. For any one window-full, if you multiply all of the inputs by a non-zero constan...

1 day ago | 1

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Answered
mexmaci64 and dylib issue
As your executable is not in /Applications you might be able to use setenv to set LD_LIBRARY_PATH. However if this is being run ...

1 day ago | 0

Answered
Reference to non-existent field
You solve() on four equations involving 18 variables. If it found a solution at all, it is not likely to be for the four variabl...

2 days ago | 0

Answered
use nvidia drivers instead of opengl
opengl save hardware then quit and re-enter MATLAB. You could also consider using hardwarebasic instead of hardware.

3 days ago | 0

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Answered
Why does linspace create row instead of column?
The main reason is that row vectors take less screen space to print out -- easier to read, and less print-out (remember, MATLAB ...

3 days ago | 2

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Answered
Curve fitting with an if statement
y = @(x) ((a0*(1-exp(-b0*(x-c0)))).*(x>=c0)) + ((a1*(1-exp(-b1*(x-c1)))).*(x>=c1))

3 days ago | 0

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Answered
How to find first '1' in every row
A = [ 0 0 0 0 0 0 1 1 1 1 0 0; 0 0 0 0 0 1 1 1 1 0 0 0; 0 0 0 0 0 0 1 1 1 1 0 0]; c = sum(cumprod(~A,2),2)+1; I do sometimes...

3 days ago | 0

Answered
How to convert a column vector into an image
nrow = 6; ncol = 6; B = full( sparse(C(:,1), C(:,2), A, nrow, ncol) ); Or nrow = 6; ncol = 6; B = accumarray(C, A(:), [nrow ...

3 days ago | 0

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Answered
s-function error
We can predict that set_K_parameter has side effects: you call it inside the loop but you never use the output values. u_dat.J...

3 days ago | 0

Answered
Arithmetic problem with for loop
l = zeros(1,N); %creating and empty array l(1) = ((3*(10^8))/(2*f1)); %formula for i = 2:N l(i) = taper1 * l(i - 1); ...

3 days ago | 0

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Answered
Xeon Phi Knights Mill
Yes, you can use MATLAB with Intel Xeon Phi processors (not co-processors). See though https://www.mathworks.com/matlabcentral/...

3 days ago | 0

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Answered
Why does it take so long for Application Compiled exe to execute?
The first time you run, it has to break out the CTF archive as well as everything else. Each time you run it has to check the...

3 days ago | 1

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Answered
Error: index must be a positive integer or logical.
You are confusing formula and indexing. In MATLAB, except under some circumstances involving symbolic variables, every time you...

3 days ago | 2

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Answered
How is it possible that vpasolve gives empty vectors when there are solutions?
vpasolve() does a modified newton search. This can involve projecting outside of any given bounds even though the solution is ...

3 days ago | 0

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Answered
Simulated annealing for optimization
Generally speaking, simulated annealing can be used to solve QAP, but it would likely be much much slower than a routine designe...

3 days ago | 1

Answered
Importing CSV files into MATLAB
In R2019a there is now readmatrix() for reading numeric values (not mixed data type). Before that, you can use readtable() and ...

3 days ago | 1

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Answered
Problem with Psychtoolbox on Dell XPS15 9560
This is not a MATLAB issue. See http://psychtoolbox.org/docs/SyncTrouble for explanation and possible solutions.

4 days ago | 0

Answered
How can I change symbolic displays to decimal displays?
There are several ways to approximate a number or change the display in Symbolic Math Toolbox. To approximate a numeric value i...

4 days ago | 3

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Answered
How to set CurrentTime for VideoReader in parfor loop
"Timestamp of the video frame to read, specified as a numeric scalar. The timestamp is specified in seconds from the start of th...

4 days ago | 0

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Answered
How to find all coordinates of extremes of two variable function?
https://www.mathworks.com/help/matlab/ref/polyder.html and roots()

5 days ago | 0

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