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Walter Roberson


44,340 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
How can I change the lamp color while the application is running?
Use drawnow() to give MATLAB a chance to update the screen.

13 hours ago | 0

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Answered
Code running, but not being displayed in command window?
You have function F=q4(x) % System of non-linear equations F(1) = x(1)^2+x(2)^2-26; F(2) = 3*x(1)^2+25*x(2)^2-100; %part b ...

13 hours ago | 0

Answered
work with numbers in number
x = 40.201109; xs = sprintf('%.6f', x); a = str2double(xs(1:2)); b = str2double(xs(end-3:end-1)); c = str2double(xs(end-2:en...

14 hours ago | 0

Answered
Solving a cubic function to get one numeric result?
S = solve(eqn,V,'Real',true,'MaxDegree',3) and sols = solve(a*x^3 - b*x^2 + c*x - d, x) and p = [1 -0.10933127 0.00082152 -0...

14 hours ago | 0

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Answered
Error using ones Size inputs must be integers?
If you want an image the same size as img2 then r = zeros(size(img2), class(img2)); after which you can assign ones into an ap...

14 hours ago | 0

Answered
Display real time data in GUI.
Variables are only global inside of functions that declare them to be global. You can never force a variable to be global everyw...

18 hours ago | 0

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Answered
Create array tm and Tm corresponding to the midpoints of t and T Temperature steps
tm = t(1:end-1) + delt/2 where delt is the vector we discussed in your previous Question.

18 hours ago | 0

Answered
To do arithmetic operations with large arrays going out of memory space
It is not possible to tell MATLAB to store variables on disk, at least not in the way you are describing. You can tell your sys...

18 hours ago | 0

Answered
Need to find the local maxima and minima of a cubic function, then write an iterating function.
for j = 0.001:10.1 j increments by 1 else j = j+.001 You are trying to modify the loop control variable. That is legal...

18 hours ago | 0

Answered
How to arrange data in cell array
reshape(code, 6, []).'

23 hours ago | 0

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Answered
fprintf multiple outputs separately
still_in_game = true(1, number_of_players); while any(still_in_game) for player_number = find(still_in_game) %if di...

23 hours ago | 1

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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.

1 day ago | 0

Answered
combination of integer numbers
[Ag, Bg, Cg, Dg] = ndgrid(0:15); Eg = [Ag(:), Bg(:), Cg(:), Dg(:)]; mask = sum(Eg,2) == 15; selected = Eg(mask,:); a = selec...

1 day ago | 0

Answered
MATLAB file to C compiler Command changes\ Makefile from MATLAB code
MATLAB Coder does not support graphics, except some of the Computer Vision routines to "draw" into arrays, and some specialized ...

1 day ago | 0

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

1 day 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...

1 day 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...

1 day 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.

1 day ago | 0

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

1 day ago | 0

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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...

2 days 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...

2 days 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...

2 days ago | 0

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

2 days 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.

3 days 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...

3 days 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 ...

3 days ago | 0

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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()...

3 days ago | 1

| accepted

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...

3 days 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...

3 days ago | 1

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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...

3 days ago | 0

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