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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 T0099000; if you are waiting on a reply from me for an older issue, please send me a reminder.

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

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Answered
Removing commas between columns in text data
test = {'Sometimes, ,, I, use, commas, .' 'I, like, writing, ,, I, like, reading'}; test = regexprep(test, {'(?<=[^,]),\...

44 minutes ago | 0

Answered
griddata command returns all NaN values
for a = 1:100 X1(a) = (5/100).*a; X1 is linear in a. c = a/50; a is a double precision integer, 1 to 100. c is the inte...

8 hours ago | 0

Answered
Sending four byte commands To serial port
cmd = [0x81 0x12 0x00 0x00]; write(YourPortObject, cmd, 'uint8'); response = read(YourSerialPortObject, 4, 'uint8'); if ise...

9 hours ago | 0

| accepted

Answered
Integer eigenvalues in Matlab
Take the symbolic determinant of (matrix minus lambda) . Ask to factor() that. Look for the entries of the form (lambda +/- inte...

11 hours ago | 0

Answered
I can't understand the following MATLAB code documentation
The implication is that the second part is stored in its own file.

11 hours ago | 1

Answered
Count from 1 to 0 with increment of 0.01
You need to use a negative increment to count down from a higher value to a lower value.

22 hours ago | 0

Answered
Equivalent python for a matlab line?
X = Y[z[i, 0:11],0] would be my guess. However, this relies upon the values in z having been changed to index 0 based instead ...

22 hours ago | 0

Answered
What is the difference between [v' 1] and [v', 1]?
v = ((1:3) -(2:4)*1i).' [v' 1] [v', 1] You can see that even for complex numbers, [v' 1] and [v', 1] produce the same results...

22 hours ago | 0

Answered
How can I sum each 3 columns array?
reshape(x, size(x,1), 3, []) now you can sum along the second dimension, and then reshape to remove the now-singular second di...

23 hours ago | 1

Answered
MATLAB Compiler for a .mlapp that have a .m file
https://www.mathworks.com/help/compiler/unsupported-functions.html Functions Not Supported for Compilation by MATLAB ...

24 hours ago | 0

Answered
Increase number of parallel pools coworker by adding hardware?
Check your Parallel Preferences https://www.mathworks.com/help/parallel-computing/run-code-on-parallel-pools.html And check t...

24 hours ago | 0

Answered
Datetime doesn't work in uitable
Your reference to handles.file_table tells us that you are using GUIDE and "traditional figures". And in traditional figures, ui...

1 day ago | 0

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Answered
How can I split time series in a half?
ts1 = timeseries(rand(1,4096)); %official approach. uses indices ss2a = getsampleusingtime(ts1, 1, 2048); ss2b = getsampl...

1 day ago | 0

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Answered
Symbolic integration of Marcumq.
Using the online tool here, execution can get through the calculation of "outer", but the integrals might take a while. Could y...

2 days ago | 0

Answered
give me invalid use of operator at U, why?
U = 0.75*exp(-((xmid-0.5)/0.1). 2)'; my guess is that you wanted U = 0.75*exp(-((xmid-0.5)/0.1).^2)';

2 days ago | 0

Answered
What should go in a next-generation MATLAB X?
The ability to assign a subset of fields to a struct (array) would be useful. It is common to want to be change a few settings, ...

3 days ago | 0

Answered
Finding global maxima and minima
Use calculas. The minima and maxima of a function can only occur at: Critical points of the function; or The boundaries that ...

3 days ago | 0

Answered
Error in array bounds
"P is 3x2396" No it is not. You assign [] to P.

3 days ago | 0

Answered
stacking or appending tables with NaN and 'ABC' -- cell vs non-cell
If I understand correctly, you are looping reading multiple files, and want to put the results all into one large table. And tha...

3 days ago | 0

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Answered
ODE15s Errors defining variable and ODE functions
Your equations involve components which subtract out T0 and P0. When you initialize the boundaries to T0 and P0 that results in ...

3 days ago | 0

Answered
Polynomial has more than one symbolic variable error
syms m1 m2 J1 s b k1 k2 k3 r1 xi T real t=0:0.5:100; A=[-s^2*m1-s*b-k2, k2, 0; -k2, s^2*m2+k3+k2, -k3; -s^2*J1/r1-s*b/r1, 0, 0...

3 days ago | 0

Answered
Asking a user in the command window to enter YYYY-MM-DD HH-MM-SS-MS
T = input('Enter time in the form YYYY-MM-DD HH-MM-SS-MS: ', 's') This will give back a character vector that has not been vali...

3 days ago | 0

Answered
Matlab system and ! commands point to wrong python version?
This is expected. Using ! or system() find the python that is first in your system path, which might not be the same one you hav...

3 days ago | 1

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Answered
Index timetable variables and remove rows based on criteria.
TT(any(TT{:,2:2001} >= 8,2), :) = [];

3 days ago | 0

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Answered
Random matrices with constraint
t = rand(n, n); nt = t./sum(t,1); output = nt.*rand(1,n); nt is normalized so that the sum of each column is 1. The s...

4 days ago | 1

Answered
Extract data from timetable for specific months
[~, mon, ~] = ymd(TT.t1); mask = ismember(mon, [1 2 12]); TTsubset = TT(mask,:); Or if you were looking for specific months...

4 days ago | 0

| accepted

Answered
My code will not run after adding in the code after function dydt=myFunc(t,y)
function dydt=myFunc(t,y) t will be a double precision number representing the current "time". t will seldom be an integer duri...

4 days ago | 0

Answered
Help For Running MVC2
I suspect you might have started running the program by double-clicking on the .fig file. You need to execute the .m file instea...

4 days ago | 1

Answered
readtable : set up the multiple lines of variables
filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/760511/A001.txt'; opt = detectImportOptions(filename...

4 days ago | 1

| accepted

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