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Walter Roberson


43,638 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
Como interpreto los resultados de rootof?
>> solve(y5,'MaxDegree',4) ans = - ((270053049741483176957*((2^(1/2)*3^(1/2)*573897224629626001025423965510526852271292...

4 hours ago | 0

Answered
Writing a function that returns all the roots of any function within a certain range?
"Writing a function that returns all the roots of any function within a certain range?" That is known to be impossible in conti...

5 hours ago | 0

Answered
Tab formatter is not working with sprintf
Fonts. As in the default is variable-spaced fonts. And tab does not have a particular width. tab is a concept for character-ori...

5 hours ago | 0

Answered
Making my own operator
MATLAB does not permit you to create new operators. MATLAB does permit you to redefine many of the existing operators, such as ...

6 hours ago | 0

Answered
2 integrals at once?
No, there is no special notation. What you pass as the first parameter to integral() must be the handle to a function that acc...

6 hours ago | 0

Answered
Integration output is NaN
You have a sub-expression ./(neta.*rho.*P.*z) When z is 0, that is a division by 0. When you are working numerically and z is ...

17 hours ago | 0

Answered
Error using eval when load many files in recursive
Don't use eval(). Construct your filenames using sprintf() and use the function form of load instead of the command form. http:...

1 day ago | 1

Answered
Index exceeds the number of array elements (1) error on line 10
if P3(i)>P2(i); Q3(i) = (P3(i)-P2(i))/R2; else Q3 = 0; end The else of that overwrites all of Q3 with a scala...

1 day ago | 0

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Answered
Disable windowkeypressfcn when specific child is on focus (app designer)
foo = uicontrol('style','slider', 'min', 0, 'max', 1); foo.Callback = @(hObject, event) fprintf('slider %g gco %g\n', double(hO...

1 day ago | 0

Answered
Sort Index - Bug
>> [a, sort_index]=sort([100;20;30;40]) a = 20 30 40 100 sort_index = 2 3 4 ...

1 day ago | 1

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Answered
imbinarize vs im2bw
label2rgb(label) is equivalent to label2rgb(label, 'jet') which triggers 'jet' to be executed with no parameters. When jet is ex...

1 day ago | 1

Answered
How to update struct array fields with mutiple values
t = num2cell(1:10); [A.B] = t{:}; See comments for the case where the struct does not already exist.

1 day ago | 3

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Answered
append a text file to structure
fileread() is the easiest way. However if your file happens to contain utf8 characters I would want to double check whether f...

1 day ago | 0

Answered
How do I add row and column separators, and a border in a table so it looks like a real table?
You cannot do any of those things in r2019a. As of R2019b it is possible to use variable names that are not matlab identifier...

2 days ago | 0

Answered
Find minimum of an n variable function, n is like 800+
No. With 800 variables and non linear curv, it is unlikely that a global minimizer will find the global minimum. Especially so ...

2 days ago | 1

Answered
Is it possible to select an m-file for a "MATLAB function" block in Simulink?
No, you cannot load files into MATLAB Function Block. You can use the MATLAB Function Block as a very thin wrapper that just...

2 days ago | 0

Answered
How to show tf function to text box?
sys_char = evalc(sys); sys_cell = splitlines(sys_char); sys_cell = sys_cell(2:end-2); %some useless empty lines set(handles...

3 days ago | 0

Answered
Is it possible to restore a deleted mat file?
Sorry, not through any method provided by Mathworks. Your operating system or third-party utilities might provide undelete meth...

3 days ago | 1

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Answered
is there any way to put two plots in one legend entry?
That happens automatically unless you do one of the following: call legend with a single legend entry, such as inside a loop or...

3 days ago | 0

Answered
How do I remove leading characters from a string?
segments = regexp(dummy{1,1}{i,1}, '\t', 'split'); Perhaps you could have used readtable() on the ascii file: it would like...

3 days ago | 1

| accepted

Answered
Block Error, Singularity in Solution?
What I had to do to get your model to execute without error message, was to uncomment the saturation block that feeds the 1D loo...

3 days ago | 0

Answered
How to reference a variable saved as .mat file to execute code
t = cyc_mph(:,1); Vmph = cyc_mph(:,2); for tidx=2:length(t)-1 a = (Vmph(tidx+1)-Vmph(tidx-1))/(2*(t(tidx+1)-t(tidx-1)));...

3 days ago | 1

| accepted

Answered
Help needed: empty plot when plotting for loop
Do not assign to Pw. Instead assign to Pw(i-1)

3 days ago | 1

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Answered
How to use webcam given in our systems?
If the camera is built in to your system then you need https://www.mathworks.com/matlabcentral/fileexchange/45183-image-acquisit...

3 days ago | 0

Answered
feval error in GUI implementation
You have function uipanel1_CreateFcn(hObject, eventdata, handles1) function Reader1Correct set(handles1.uipanel1, 'Back...

3 days ago | 1

| accepted

Answered
How to filter certain parts of a string.
S = char(wdoc.Content.Text); x = regexp(S, '^Introduction:.*?(?=^\nSummary:)', 'match', 'lineanchors');

3 days ago | 0

| accepted

Answered
re-insall MATLAB because of changing to a new computer
https://www.mathworks.com/matlabcentral/answers/142388-how-do-i-transfer-a-student-or-home-license-to-a-new-computer#answer_145...

3 days ago | 0

Answered
How do I replace multiple strings in text file at the same time?
S = fileread('YourFileNameHere.txt'); newS = regexprep(S, {'C-C', 'A-A'}, {'D-D', 'C-C'}); This replaces C-C with D-D everywhe...

3 days ago | 1

| accepted

Answered
Communication Toolbox comm.GeneralQAMTCMDemodulator Question
No. It is a .p file and cannot be editted.

4 days ago | 0

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