Walter Roberson
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51,247 total contributions since 2011I 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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Answer 50 questions that were unanswered for more than 30 days
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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
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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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
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
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
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
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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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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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
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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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
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
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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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
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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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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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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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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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
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
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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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
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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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
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
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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use gpu for image processing
generateParams(image, param_one); % saves results in image1_result.mat % create corresponding database for the ...
3 days ago | 0
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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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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