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Walter Roberson


Last seen: Today Active 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. I am currently caught up to T0099119; if you are waiting on a reply from me for an older issue, please send me a reminder.

Programming Languages:
C, MATLAB, Shell, Perl, Fortran
Spoken Languages:
English

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Answered
How can I specify the dimension of a differentiated function?
diff() is generally successive differences. It is only derivative if the first parameter is sym or symfun, both from the Symboli...

6 hours ago | 0

Answered
Finding a redundant pattern in a matrix
C1=[ 5 9 3]; C2=[ 9 5 3]; C3=[9 5 9 3]; C4=[5 9 8 3]; C5 = [5 3 9 8]; is_in(C1, C2) is_in(C1, C3) is_in(C1, C4) is_in(C1, ...

18 hours ago | 0

Answered
Connecting to USB device with serialport vs. serial command
serialport does not have any fopen() or fread() . It automatically opens the port when you create the object, and it uses read()...

19 hours ago | 0

Answered
Empty matrix, scalar, or vector function in loop
MATLAB uses == for comparisons, not = Also, X = [] Y = 1 if X == []; disp('X yes 1'); end if Y == []; disp('Y yes 1'); end ...

19 hours ago | 0

Answered
Numeric data becomes zero after conversion from Table
I predict that you have format short in effect, and that what is being displayed is not really 0 but is instead something of t...

19 hours ago | 0

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Answered
Why results of the 'solve' are wrong?
p_max=715.685424949238; (and a bunch of other numbers). What does that input mean? Does it mean that p_max is exactly ? Does ...

21 hours ago | 1

Answered
Excel sheet data upload "Invalid 'DataRange'. The column size must match the number of variables".
opts.DataRange = "A2:AT78"; That requests that column "A" to "AT" be read in. However, M1_New_Macro1.xlsx only has data up to c...

22 hours ago | 0

Answered
Logical operator not evaluating correctly
A|B is an or test and returns a logical value -1 is nonzero which is considered true, and since you or everything together you a...

24 hours ago | 0

Answered
Hi.How I can plot W_m to n connection
See <https://www.fieggen.com/shoelace/lacingmethods.htm> for some of the possible ways to plot that.

1 day ago | 0

Answered
Receiving mouse clicks in App Designer UIAxes - stops working after imshow
https://www.mathworks.com/help/matlab/creating_plots/capturing-mouse-clicks.html MATLAB considers graphics objects to be layer...

1 day ago | 0

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Answered
molecular code in matlab
There are a lot of undefined variables there. There are two possibilities: There might be another script that you have to exec...

1 day ago | 0

Answered
Need help coding this
Example. fun = @(x, y) (x + y).^3 - 5*(x.*y) - 1; [X, Y] = meshgrid( linspace(0,2)); z = fun(X, Y); contour(X, Y, z);

1 day ago | 0

Answered
I have a data 5x148992 , i have to extract data column wise and check if there is any changes wrt previous column and display when there are chnages?
for i = (data( : , : )) data appears to be a 2D array. When you have something of the form for VARIABLE = EXPRESSION; BODY;...

2 days ago | 0

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Answered
How to add Line/Markers to an Axis Label?
L = "G\prime ( \bullet ) and G\prime\prime ( \color{red}{\bullet}\color{black} ) (Pa)"; ylabel(L, 'interpreter', 'tex') See al...

2 days ago | 0

| accepted

Answered
How to calculate the symbolic integration of rational functions?
Wolfram Alpha says https://www.wolframalpha.com/input?i=int%281%2F%28x%5E4+%2B+x%5E3+%2B+x%5E2+%2B+x+%2B+1%29%2C+x%2C+0%2C+1%29&...

2 days ago | 0

Answered
Solving large linear systems of equations in parallel / distributed systems
Gb = 60000^2*8/1024^3 The matrix is close to 27 gigabytes. The inverse is the same size, so you will need at least 54 gigabytes...

2 days ago | 0

Answered
How to make a new column in my table
elseif requires a expression after it, but you coded an assignment. You just want else not elseif Remember that if Results(...

2 days ago | 0

Answered
Need a to plot a graph
hvals = linspace(0,17); numh = length(hvals); Vtotal = zeros(numh, 1); H1 = 11; %in H2 = 5; %in m r1 = 3.5; %in m r2 = ...

2 days ago | 0

Answered
Trial download 2021b
only Mathworks Sales can generate trials against older versions.

2 days ago | 0

Answered
How to shift elements in matrix?
circshift()

2 days ago | 0

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Answered
how can i imagie zoom with Convolution method
It is deliberate that the following does not do exactly what you want to do. It is also deliberate that it has some extra steps ...

3 days ago | 0

Answered
How can I simplify my code using loops?
Put the channels into a cell array: lena_ch = num2cell(lena, [1 2]); Now you can loop over the rows of indices = perms(1:3) ...

3 days ago | 0

Answered
I need help writing equation in matlab
format long g syms x n m result = symsum(x^n/factorial(n), n, 0, m) limit(result, m, inf) result20 = subs(result, m, 20) ex...

3 days ago | 0

Answered
How can I make the execution speed consistent while I am testing the speed of the programs?
I am not convinced that virtual machines will be allocated dedicated resources that will not be affected by other activities. ...

3 days ago | 0

Answered
Hello, I've got the problem. Can any one help me with that error?
cond = [x(0)==0, diff(x, t)==0]; The first part of that sets a boundary condition. The second part of it says that the deri...

4 days ago | 0

Answered
how can I calculate A^n when n is a symbolic positive integer?
syms N positive integer [V, D] = eig(sym(A)) result = V*diag(diag(D).^N)/V Note those are the matrix operations *...

4 days ago | 0

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Answered
how to run a function on GPU cores
You would have to use <https://www.mathworks.com/help/gpucoder/index.html> Nvidia GPUs are constructed in a hierarchy. GPU co...

4 days ago | 1

Answered
Hi, I am trying to produce randomly circles with same radius in defined range or square. I wrote the code, but it show error " Out of memory. The likely cause is an infinite"
function h = circle(x,y,r, N) ... for i=1:1:size(circle) circle is not a local variable in the function circle, and is not th...

4 days ago | 0

Answered
Axis Ticks using Calendar Year ticks with BC years
YearTicks = datetime({'1950 CE'; '1725 CE'; '1501 CE'; '1277 CE'; '1053 CE'; '0828 CE'; '0604 CE'; '0380 CE'; '0156 CE'; '0069 C...

4 days ago | 0

| accepted

Answered
Simlify a function in matlab
syms B C x eqn = cos(x) + B*sin(x) == C expr = -sin(x) + B*cos(x) xsol = solve(eqn,x) newexpr = simplify(subs(expr, x, xso...

4 days ago | 1

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