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Walter Roberson


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46,839 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
Dynamic call to structure elements
for K = 1 : 3 MyStruct.(sprintf('Elmt%d', K)) end or for K = 1 : 3 MyStruct.("Elmt"+K) %rely on string obje...

11 minutes ago | 0

Answered
Unrecognized method, property, or field 'Position' for class 'matlab.graphics.GraphicsPlaceholder'.
Your findobj() is not locating any PolarAxes, and is returning the empty GraphicsPlaceholder object. When you ask to access a f...

13 minutes ago | 0

Answered
How to extract data from on a timetable dependent on a date range
https://www.mathworks.com/help/matlab/ref/timerange.html However, I would suggest that you might not be asking the best questi...

43 minutes ago | 0

Answered
how to use for loop along with ode45 to generate a series of plots
for N = 1 : 10 za = fzero(@(z) res(za,N), 50) [x, T] = ode45(@(x,T)func(x,T,N), [0.3 1], [0; za]); plot(x, T(:, 1...

1 hour ago | 0

Answered
What does "IND" do?
There is no "ind" function in that code. What the code is doing is adding values to the end of a list. If Blt(1) is 1, then ad...

1 hour ago | 1

| accepted

Answered
Code initiates again after exiting while loop which is within an if statement
I gave a detailed explanation of how for loops work in https://www.mathworks.com/matlabcentral/answers/356884-how-do-i-convert-t...

2 hours ago | 0

Answered
Comparing different size of Matrix Problem
In some cases it might make sense to use Dynamic Time Warping to compare the vectors; see https://www.mathworks.com/help/signal/...

2 hours ago | 0

Answered
diff command in matlab
Q0 = diff(diff(L,diff(t1))) - diff(L,t1); diff(t1) will generally be an expression, seldom happening to be a scalar variable. Y...

3 hours ago | 0

Answered
How to became my Tridiagonal matrix
full(spdiags(B',0:-1:-3,7,4))

3 hours ago | 0

| accepted

Answered
Help with efficient way of importing data file with specific structure
filename = 'appropriate_name'; fid = fopen(filename); nvars = fscanf(fid, '%f', 1); tdata = textscan(fid, '%[^\n]\n', nvars...

5 hours ago | 0

Answered
parfor variable cannot be classified
https://www.mathworks.com/help/parallel-computing/troubleshoot-variables-in-parfor-loops.html Sliced variables: https://www.m...

5 hours ago | 0

Answered
Home License Limitations and Service Maintenance renewal cost
i expect "perpetual" access to the add ons that I have paid for as well as the one available to Matlab users for free but now th...

6 hours ago | 0

Answered
besself does not plot correctly
You use freqs(bn, an, 1e6) . That asks it to pick out 10^6 frequencies, but it does not say anything about the range to pick the...

7 hours ago | 0

Answered
Will MATLAB Live editor ever support spellcheck?
"Will MATLAB Live editor ever support spellcheck?" You should assume that the answer to *all* questions about whether MATLAB ...

22 hours ago | 1

Answered
How can I copy figure to UIAxes?
Use imhandles() on the figure that is showing the gramm object. You can now copyobj() the resulting handle(s) to a uiaxes that...

1 day ago | 0

Answered
convert csv file and write to another .m file
filename = '100Cr6.csv'; S = fileread(filename); S = regexprep(S, {',', ';'}, {'.', ','}); mdata = cell2mat( textscan(S, '', ...

1 day ago | 0

Answered
hello everyone, i have this urgent problem
I discus one of the techniques in https://www.mathworks.com/matlabcentral/answers/496730-how-to-start-and-stop-parallel-timer-de...

2 days ago | 0

| accepted

Answered
Is there any discrete mathematics solver for symbolic equations ?
you will need to use evalin or feval into the symbolic engine, and use rec() to build the recurrence equation and then solve() t...

2 days ago | 0

Answered
Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.
[bestpar, resnorm, residual, exitflag, output, lmd, jacobian] == lsqnonlin (@ fz_costo_sana, startpar [0.01 0.01; .01] [10 10 ...

2 days ago | 0

Answered
Keeping command line programs open while inputting and outputting text files
You should be using .Net processes https://blogs.mathworks.com/loren/2010/12/07/using-microsoft-net-to-expand-matlab-capabili...

2 days ago | 0

Answered
run .exe file with matlab in unix
exe files are Windows executables that are not directly usable in Unix. If you have a windows emulator such as wine you might...

3 days ago | 0

Answered
matlab conersion code needed
Change the endif to end Change the endfor to end I did not see anything else at the moment

3 days ago | 0

Answered
how to find a exact word in a string?
length(regexp(str, '\<talk\>'))

3 days ago | 0

Answered
How to solve this system of nonlinear equations composed of symbolic variables
F=@(x,y)[eqn3;eqn4;eqn5]; Okay, F takes two arguments and ignores them and returns an array of items based on symbolic x ...

3 days ago | 0

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Answered
How to compute arccos for a matrix?
It depends what you are trying to calculate. Using the formulas at https://en.wikipedia.org/wiki/Arccos_(trigonometry)#General...

3 days ago | 0

Answered
Replace string with another value
S = {'13 Jon Walker', '23 skidoo', '0 infinite way blvd'}; upper(regexprep(S, '^.*\s+(...).*', '$1'))

3 days ago | 0

| accepted

Answered
How can I do implicit differentiation
Example syms y(x) DY eqn = acot(x^2+x*y) - asin(x+y) == y^3-x; dy = diff(y); deqn = diff(eqn,x); Deqn = subs(deqn, dy, DY);...

3 days ago | 0

Answered
How to insert special symbol into plot label?
DSQ = char(hex2dec('211a')); qval = randn(); mylabel = sprintf('%s factor = %g', DSQ, qval); xlabel(mylabel) Note: this will...

3 days ago | 0

| accepted

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