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Walter Roberson


44,327 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
Conditional calculations on a numeric matrix
mask = input > thresholdvalue; result(mask) = input(mask) * 2; result(~mask) = input(mask) / 2;

3 hours ago | 0

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Answered
Preprocessing using readtable()
Use detectImportOptions() on the csv file, and store the result to a variable. Now modify the DataLines property of the import o...

3 hours ago | 0

Answered
How to convert a variable which has binary data in .mat format to .txt?
save() with the -ascii -double options is one way. However, if I recall, this can lose the last bit or two of precision, so if y...

3 hours ago | 0

Answered
please help me with this
You have F=[]; inside the loop, so you are throwing away all of the F contents except for the last image.

5 hours ago | 0

Answered
Simple Message Encryption with Matricies
>> mod(F(1,:),1) ans = 4.2632564145606e-14 0 0.999999999999943 char() truncates ra...

5 hours ago | 0

Answered
Chaotic map, Metaheuristic
The number of sequences is equal to the number number of values representable in the data type you are using, raised to the powe...

16 hours ago | 0

Answered
defined n with the equation
"Create as the midstep values are computed" is talking about a for loop with controlling variable n, and for n=2 onwards you cal...

17 hours ago | 0

Answered
Real Time audio modification and reproduction trough GUI
You cannot do that for audioplayer objects. In current releases you would use the Audio System Toolbox. In your release yo...

18 hours ago | 0

Answered
can anyone help explain to me ?
s2=sum(fliplr(1./(i.^2+i)))+1;

19 hours ago | 0

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Answered
any trick to stop fminsearch early?
fminsearch permits options that include Outputfcn and that function can signal to terminate.

1 day ago | 1

Answered
Hot to locate indices of 2-D data located out of circle?
vector_of_y_values = (1:number_of_rows) - y_center; vector_of_x_values = (1:number_of_columns) - x_center; [Yg, Xg] = ndgrid(v...

1 day ago | 0

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Answered
Guide math operation equal.
You need to parse what is in get(handles.text1,'string') . If it is not (optional spaces followed by) = (followed by optional ...

1 day ago | 0

Answered
How do I get MATLAB to use first set of data from csv Excel sheet I have?
csvread() cannot handle text, except that you can tell it to skip leading rows and/or leading columns. So you can tell csvread()...

1 day ago | 1

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Answered
Why it said that "Matrix index is out of range for deletion"
Strin=strcat(strFirst,"_",strLast); Because you used "_" the result you get is going to be a string object, not a character vec...

1 day ago | 0

Answered
My Matlab recently told me to update my version. How is this done?
In the command window, on the upper right, click on RESOURCES . Click on Help there. One of the menu items that comes up will th...

1 day ago | 1

Answered
How to frequently run ODE45?
for T = 300:100:1000 [z,y] = ode23s(@(t,y) equations(t,y,T), [0 1], [0 0 0 1]); rco2 = desparameter(1e-20,T,80 * 1.660...

1 day ago | 0

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Answered
why inverse of Jacobian matrix FAIL??
J = [ 0, 1, 0, 0, 0, 0] [ 0, 0, 1, 0, 0, 0] [ 0, 0, 0, 1, 0, 0] [ 0, 0, 1, 0, 0, ...

1 day ago | 0

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Answered
how can i know which are missing toolboxes?
year() is part of the Finance Toolbox. You would not have received that particular error if you did not already have that toolbo...

2 days ago | 0

Answered
Attempt to call constructor figure with incorrect letter case.
https://www.mathworks.com/matlabcentral/answers/113471-why-this-error-is-occured Somewhere on your MATLAB path you have your o...

2 days ago | 0

Answered
How to audiowrite time shifting audio?
You cannot write an audio file at particular times. You must construct every sample from time 0. In the simple case that woul...

2 days ago | 0

Answered
Two textscan stamentents for the same file in coad
e = textscan(fid1,'%q','HeaderLines', 3); %q is quoted string format. There is nothing that it cannot match, other than end of ...

2 days ago | 0

Answered
Dir function gives nothing
selpath = uigetdir; if isempty(selpath); return; end %user cancel dinfo = dir(fullfile(selpath, '*cell*.json')); uigetdir()...

2 days ago | 1

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Answered
Getting points with ginput from image and plotting simultaneously each selected point
n = 0; while true [x, y, button] = ginput(1); if isempty(x) || button(1) == 1; break; end n = n+1; x_n(n) = x(1...

2 days ago | 1

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Answered
Use External Hard Drive for Memory in MATLAB
"Out of memory" is talking about RAM, not about hard drive space. One of your arrays is too large to be able to process with tha...

2 days ago | 0

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Answered
How to save timetable as txt file?
https://www.mathworks.com/help/matlab/ref/writetimetable.html indicates it was introduced in R2019a. You either need to upgrade ...

2 days ago | 0

Answered
How to modify narginchk in DES matlab code
You should not modify it to assign input64 and mode and key in the code. You should define the function as accepting up to 3 inp...

2 days ago | 0

Answered
How to read data from a file with fixed format?
importdata() is going to treat the first thing on the line as numeric (skipping the leading '[') but it treats everything else o...

2 days ago | 0

Answered
How do I remove 9 random numbers from a shuffled array?
shuffled_data(ismember(shuffled_data, values_to_ignore)) = [];

2 days ago | 0

Answered
Extract eigenvalues and eigenvectors / Symbolic to numeric / Rayleigh-Ritz Method / Vibro-acoustics
https://www.mathworks.com/help/symbolic/eig.html Symbolic eigenvalue does not support generalized eigenvalues.

2 days ago | 0

Answered
Read in integer values from .txt file
data = load('NameOfTheFile.txt');

3 days ago | 0

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