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Walter Roberson


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49 916 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
Using exponential functions to find half capacity
you need to find the first place that P is 150 or higher. Once you have the location then use it to index the time

environ 2 heures ago | 0

| accepted

Answered
Need help filling a Matrix with values from an 'fprintf' Command
variable = sprintf(formatSpec,u(j,i)); See also compose() . In particular, if you use a double-quoted format with compos...

environ 5 heures ago | 0

Answered
3D Matrix Multiplication
https://www.mathworks.com/matlabcentral/fileexchange/25977-mtimesx-fast-matrix-multiply-with-multi-dimensional-support https:/...

environ 5 heures ago | 1

Answered
How to delete rows of empty cells from a cell array
A = cell(4,3); % Fill first 2 rows of cell for k = 1:2 A{k,1} = 1; A{k,2} = 2; A{k,3} = 3; A{k,4} = 4; en...

environ 6 heures ago | 1

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Answered
If statement error with less than OR greater than
if lambda <= 0 || lambda >= 2

environ 6 heures ago | 0

| accepted

Answered
how to convert a video to OFDM frames ?
No, it is not possible to convert directly. You have two choices: You can read a frame of the video at a time, and convert the...

environ 6 heures ago | 0

Answered
sym/subsindex error. fplot error.
P=fplot(k_f,G); G is an equation, and k_f is a plain symbolic variable. When you fplot() you need to put an expression to be p...

environ 6 heures ago | 0

Answered
Cant figure out how to get my functions to graph
f=@(y) y.*(y-2).^2.*(y+4).^(3); phaseLine(f,-6,4); %% 5. y_min=-5; y_max=3; f1=@(y) y.*(y.^2+4); phaseLine(f1,y_min,y_...

environ 8 heures ago | 0

Answered
Integration Limits on Trapz
x = sort(rand(1,20)); y = exp(sin(2*pi*x)); yint = cumtrapz(x, y); plot(x, y, 'k', x, yint, 'b') syms X B Y = exp(sin(2*pi*...

environ 9 heures ago | 1

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Answered
Question about ODE45
The ode*() functions cannot handle impulses. More completely, they are only designed to handle objectives in which the second de...

environ 9 heures ago | 0

Answered
Matlab getting incredibely slow when plotting
For the first one you have x = 0.5*ones(1,Resolution); which is a row vector. For the second one you have x=ones(Resolution)...

environ 10 heures ago | 0

Answered
How to loop through all files present in several subfolders in a main folder?
https://www.mathworks.com/help/matlab/ref/matlab.io.datastore.filedatastore.html You can use a filedatastore with a reader fun...

environ 10 heures ago | 0

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Answered
Convolution without using conv
Get your program working first before you worry about optimization. write a u function. write a function for each of your form...

environ 10 heures ago | 0

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Answered
How to resample n vectors with specified length from a longer vector
starts = randperm(length_of_vector-length_of_section+1, n).'; subsets = cell2mat(arrayfun(@(S) vector(S:S+length_of_section-1),...

environ 10 heures ago | 0

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Answered
How to draw the contour lines in MATLAB.
data = readmatrix('Sai.xlsx'); contour(data, 0.1:0.1:1) colorbar

environ 13 heures ago | 0

Answered
Supress Warning in a Loop
X=X-inv(j)*f; replace with if rank(j)<length(j) X = nan; else X = X - j\f; end

environ 14 heures ago | 1

Answered
How to reorder a vector one cell at a time?
Okay, so the problem is that the rules are not exactly as you describe. The algorithm Start at the top of the column, and reme...

environ 24 heures ago | 0

Answered
how to solve an equation iteratively?
syms x eqn1 =200 == x*(1-(0.4*(x-1))/sqrt(2.8*2.4*x+0.4))^(-2.8/0.4); sol = solve(eqn1, x); sol = sol(imag(sol) == 0) vpa(so...

1 jour ago | 0

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Answered
Inverse a cell of matrices
T1inv = cellfun(@inv, T1, 'uniform', 0); However, most of the time you should avoid using inv() . It is not common that you nee...

1 jour ago | 0

Answered
error: Unrecognized function or variable 'y', using ode45
function main a = 0.01725*exp(2660/300); E = 2660; T0 = 300; Cao = 2; cpa = 20; cpb = 20; nao = 2*1200; nbo = 2*1200; ...

1 jour ago | 2

| accepted

Answered
while loop for changing vairable
theta = [-90:5:90] M = sind(theta); N = cosd(theta); T = arrayfun(@(m,n)[m^2 n^2 0 0 0 2*m*n; n^2 m^2 0 0 0 -2*...

1 jour ago | 0

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Answered
How to skip vpasolve empty sym inside a loop
Store the result of vpasolve into a variable. Test to see if it is empty before storing into the matrix.

1 jour ago | 0

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Answered
Index exceeds array bounds... need some help please!
i= [1:100]; x(i)= 100; You initialize 100 elements for i=[1:100] Tf(i+1)=x(i+1); You try to access 100+1 elements Also...

1 jour ago | 0

Answered
covert data as matrix
Q =(unifrnd(0,1,5,15)) save('Q.txt', 'Q', '-ascii', '-double') !cat Q.txt

1 jour ago | 1

| accepted

Answered
Why does symbolic integration return the wrong answer for this integral?
syms x a expr = 1/(1-x)^2 F = int(expr, x, 0, a) subs(F,a,x)

1 jour ago | 2

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Answered
Plot function adding line from last point in row to origin
In order to see that plot with multiple lines, your y_nudged must be 2D. The following code takes that into account. xt = x_nud...

1 jour ago | 0

Answered
Creating grid with incremental numbers around specific coordinate
N = 5; r = 2; c = 3; temp = true(N,N); gr = bwdistgeodesic(temp, c, r) + 1

1 jour ago | 0

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Answered
Table properties giving error
You have a third-party function named split on your MATLAB path. which -all split

1 jour ago | 0

| accepted

Answered
need help with this summation
zeta = reshape(linspace(0,2), 1, [], 1); %row fo = reshape(logspace(-2,0,50), [], 1, 1); %column n = reshape(1:2:101, 1,...

1 jour ago | 0

Answered
'Matrix dimensions must agree' error in matlab app designer
function botonButtonPushed(app, event) if app.menu.Value=="engranaje" app.caja.Value=1 ...

1 jour ago | 0

| accepted

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