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Walter Roberson


Last seen: Today
51,247 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
Run 3 screens at a time/parallel screen
https://www.bu.edu/comtech/faculty-staff/classroom-av/instructor-station-desktop-mirroring/ has Windows 10 instructions with dia...

6 hours ago | 0

Answered
I am trying to code the inverse power method but the outcome of the eigenvector was half of the correct answer. Is there a way to fix it?
eigenvectors are direction but not magnitude. If v is an eigenvector of a matrix then so is m*v for all nonzero scalar m. Theref...

10 hours ago | 0

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Answered
Find only numeric strings on cellstr array.
arr = {'123', 'Hola', 'my', 'String', '', '1453', 'stay'}; find(~cellfun(@isempty, regexp(arr, '^\d+$', 'once'))) find(matc...

12 hours ago | 1

Answered
Error using <= Not enough input arguments
Reff= Ric+Rbuc+2*Rg+2*Rluc; That is a mathematical computation. The result is going to be numeric. F=Reff.kphi;; Reff is nume...

13 hours ago | 1

Answered
How to improve efficiency when checking for unique combinations of table values?
findgroups the two columns individually. Concatenate the groups into one array of two columns. Use those as the first parameter ...

15 hours ago | 0

Answered
What is the best way to turn a time vector into something plottable when you have large quantities of data?
filter the entire data by p1 and p2 giving you 6 columns. pass the 6 to datetime, and it will do a mass conversion. You do not n...

16 hours ago | 0

Answered
Can someone explain this loop?
The count starts out 0. Then you start going through the array in linear index order. Each time you find an even number, you inc...

16 hours ago | 1

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Answered
Is there a method to use ‘findpeaks’ to detect bright spots in an otherwise darkimage?
you can post process the findpeaks output but it really does not seem to be worth the effort. https://www.mathworks.com/help/ma...

1 day ago | 0

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Answered
convert an array of 0s and 1s to binary & reverse
pad with 0 to a multiple of 8 2.^(7:-1:0) * reshape(padded, 8,[]) The result will be a vector of values 0 to 255 reve...

1 day ago | 0

Answered
combining two different codes
do not use inline() Use g = matlabFunction(A)

1 day ago | 0

Answered
Display data of a particular variable present in a netcdf file
latitude is effectively "plaid" -- there are 50 columns and 50 different latitudes (to within round-off). But you cannot just us...

1 day ago | 1

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Answered
Is possible select specific rows with all column in a loop?
mask = ismembertol(YourArray, 1:6); selected_rows = YourArray(mask,:); G = round(selected_rows(:,1)); split_groups = splitapp...

1 day ago | 0

Answered
From plot to video
See getframe() https://www.mathworks.com/help/matlab/ref/getframe.html and videowriter() https://www.mathworks.com/help/matlab/r...

2 days ago | 0

Answered
Some Errors I couldn't fix (gui)
You can go in and edit the callbacks using GUIDE... but the easier solution is to add these to the bottom of the code: function...

2 days ago | 0

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Answered
how to integrate the function?
syms theta t__c t_prime x v__x y omega t part1 = 1/(1+2*t_prime/t__c) part2 = exp(-2*((x-v__x*t_prime).^2 + y.^2)/((1+2*t_prim...

2 days ago | 0

Answered
How do I stop the calculation in a for loop?
The division by 50 is just to make the output shorter for this demonstration. format long g n = 4; v = rand(n,2) / 50; for f...

2 days ago | 0

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Answered
how can I buy license Matlab and Simulink From Viet Nam?
You cannot choose the version for Student licenses; you can only purchase the latest version. In Viet Nam, Mathworks operates t...

2 days ago | 0

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Answered
How to gradually plot two simultaneous graphs in MATLAB gui?
a = 0:0.01:1; x = sin(2*pi*3*a); y = cos(2*pi*a); fig1 = figure(1); ax1 = axes(fig1); fig2 = figure(2); ax2 = axes(fig2)...

2 days ago | 0

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Answered
Merge Variables in Table
names = YourTable.Properties.VariableNames; initials = extractBefore(names, 2); [G, id] = findgroups(initials); newTable = ta...

2 days ago | 1

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Answered
Double sumation of mathmatical equation
What is the ? It looks like a function or integration or something like that. I recommend that you reverse the order of summat...

2 days ago | 0

Answered
Confusion about specifiers and output
When I open the cell, it shows the output with 4 decimal places That does not mean that the decimal places are not stored -- it...

2 days ago | 0

Answered
how to plot a graph gradually?
a = 0:0.1:10; x = sin(2*pi*3*a); for i = 1:length(a) plot(a(1:i),x(1:i)) pause(1) end However I recommend that you...

2 days ago | 0

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Answered
Does Macbook Air M1 is well-oprimized MATLAB?
The reports I am seeing is that it is already decently fast even in emulation, and is expected to get faster as more of it goes ...

2 days ago | 1

Answered
Iterating Through Multiple Structures in One Structure
A = struct(); for K = 1 : 4 ts = struct('pqr', randi(9, 1, 3), 'stu', randi(9, 1, 3)) n = char(randi(0+['a', 'z'], 1, 5...

2 days ago | 0

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Answered
Create a vector in 15-minute intervals (from 0 am to 24 pm)
Sure, you can xticks() with datetime objects if you have a datetime ruler. The problem is being able to read it. Every 15 minu...

2 days ago | 0

Answered
generate square wave using piecewise function and plot it
PulseLength = 50; CycleLength = 1000; ReduceCycle = @(x) x - CycleLength*floor(x/CycleLength) syms t y(t) = piecewise( Reduc...

3 days ago | 0

Answered
What is the Best Way to Deal with an Empty Line Object?
i1 = x<=3; i2 = x > 100; i3 = x >= 7; plot(x(i1),y(i1),'r',x(i2),y(i2),'b',x(i3),y(i3),'g'); hold on hlines = plot(nan,nan...

3 days ago | 0

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Answered
use gpu for image processing
generateParams(image, param_one); % saves results in image1_result.mat % create corresponding database for the ...

3 days ago | 0

Answered
Replace a variable in differential equation with 0
syms T(t) SigmaT(t) BetaV(t) Lemda To ode = diff(T,t) == ((Lemda-((SigmaT(t)).*T))-BetaV(t).*T(t)) cond = T(0) == To; zerofun...

3 days ago | 0

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Answered
Replacing Variable in an ODE
syms T(t) Lemda Sigma To ode = diff(T,t) == (Lemda-(Sigma.*T)); cond = T(0) == To; Solution = dsolve(ode, cond)

3 days ago | 0

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