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Walter Roberson


Last seen: Today |  Aktiv seit 2011

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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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Beantwortet
divide every numeric value in table by same number
divisor = 2; T = table(["hello"; "orange"], [1;3], [2; 4]) vt = vartype('numeric') T{:,vt} = T{:,vt} / divisor

etwa 2 Stunden vor | 0

Beantwortet
How I can fix my problem when I add a function to the main script within for loop and run iteration was made with an error?
for i = 1:K i X = [X0 zeros(1,K)]; You overwrite all of X each iteration of for i X(i+1) = Xr; You overwrite one...

etwa 2 Stunden vor | 0

Beantwortet
Can I see the code for a Matlab Function?
function_name = 'ordfilt2'; location = which(function_name); if isempty(location) error('could not find function "%s" a...

etwa 2 Stunden vor | 0

Beantwortet
Nested Function is not working correctly with ode45
In MATLAB, (A<=B)<=C does not mean to test whether B is between A and C. Instead, it means to test whether A<=B and if so emit 1...

etwa 2 Stunden vor | 0

Beantwortet
How to find derivatives using the diff command
It is possible to apply symbolic diff() to a function handle of an anonymous function -- but you have to specifically mention a ...

etwa 3 Stunden vor | 0

Beantwortet
How do I change the output of the graph from velocity to acceleration?
Use gradient(x, y(:, 2)) to estimate the acceleration

etwa 7 Stunden vor | 0

Beantwortet
MATLAB Crashes When I Update and Copy in New Mex File
clear mex This will not affect files in use. I am not sure what would happen if you had a function handle that refers to...

etwa 8 Stunden vor | 0

| akzeptiert

Beantwortet
equation or formula for multiple values to equal a constant
format long g x = [32.06, 34.26, 35.84, 39.2, 44.92, 52.24]; y = repelem(56.68, 1, length(x)); p = polyfit(x, y, 2) To withi...

etwa 19 Stunden vor | 0

Beantwortet
how can I display text of zero amplitude with text message
After having found the places that are zeros and storing the x coordinates in List_of_XCoordinates_Of_Zeros then for xcoord = r...

etwa 21 Stunden vor | 1

Beantwortet
Why is my "plot" function not working?
The first row has time 00. That is text not numeric. Looking at the left justification it looks to me as if the second column...

etwa 23 Stunden vor | 0

Beantwortet
Error while using 'tunefis"
You are using readtable. When you use () indexing on a table object the result is a table object. Use {} indexing or use dot ind...

ein Tag vor | 0

| akzeptiert

Beantwortet
Problem with integration using sym in case of "sym is not convertible to double"
One or more of the things that look like variables in your expression are symbolic functions. You should invoke each of the symb...

ein Tag vor | 1

Beantwortet
How can I solve this error xdot = A*x + B*u; y = C*x + D*u; Incorrect dimensions for matrix multiplication A*x
Your A is 6x6. Your x is 4x1. You cannot matrix multiply the two. Your A should have (number of outputs) rows and (number of ...

ein Tag vor | 0

Beantwortet
Conversion to double from optim.problemdef.OptimizationExpression is not possible
https://www.mathworks.com/help/optim/ug/fcn2optimexpr.html#mw_7959222a-434e-46eb-aec3-fe7942326891 I am not sure if you will ...

ein Tag vor | 0

Beantwortet
How can I convert cell to a timetable?
times = datetime(YourCell{:,4}, 'InputFormat', "yyyy-MM-dd'T'hh:mm:ss'Z'", 'TimeZone', 'GMT'); data = table2timetable(cell2tabl...

2 Tage vor | 1

| akzeptiert

Beantwortet
Finding the indexes of multiple substrings within a larger string.
c = 'a91bb48353' mask = ismember(c, '0':'9'); odd_pair = find(mask(1:2:end-1) & mask(2:2:end)) * 2 - 1 even_pair = find(mask(...

2 Tage vor | 0

Beantwortet
measure the distance between two object
If you want the "real-world" distance, then you will either need to know the resolution of the pixels, or else you will need to ...

2 Tage vor | 0

Beantwortet
Symsum function with odd number and infinity upper limit
Pi = sym(pi); syms D x y kh kx ky syms q Q q = 2*Q - 1; expression = (((-1)^((q-1)/2)/(q*(D)^2)))*((cosh(D*x/kx)/cosh(D))-...

2 Tage vor | 0

Beantwortet
Getting an error "Error using erfc... Input must be real and full"
if a is negative and t is positive then sqrt(a*t) is square root of a negative value which is imaginary. You end up taking erfc ...

3 Tage vor | 0

Beantwortet
Need to test the validity of an application handle
Isvalid would do the trick, but it's not available in 2022b. isvalid with lower-case I has been available since at least 2006.

3 Tage vor | 0

Beantwortet
Why do I get the error message "Unrecognized function or variable 'sim'" in my Standalone Excecutable
You need Simulink Compiler; https://www.mathworks.com/products/simulink-compiler.html

3 Tage vor | 1

Beantwortet
Failed to create file modification time character vector
The file is probably corrupted; see https://www.mathworks.com/matlabcentral/answers/1859293-imfinfo-doesnt-work-in-r2022b-it-s-b...

3 Tage vor | 0

Beantwortet
How to fix the compilation problem?
This is a security concern. See https://www.mathworks.com/matlabcentral/answers/813140-confusing-warning-during-compilation-warn...

3 Tage vor | 0

| akzeptiert

Beantwortet
Hi i have a set of data which is temperatures in degree celsius ranging from 10 deg to 250 deg but i need to plot only the temperatures ranging from 20 and 70 degrees .
xlim([20 70]) Or possibly ylim() instead of xlim() Or maybe you need clim()

4 Tage vor | 0

Beantwortet
How to input exponentials in transfer functions using Simulink?
If this must be implemented as transfer functions then you will need to copy the transfer function block several times, set the ...

4 Tage vor | 0

Beantwortet
Save multiple variables into single -Ascii File with different column of [x:y:z]
out = [SSS, Lat, Lon]; save('20150131.asc', 'out', '-ascii')

5 Tage vor | 0

Beantwortet
recalculation with different rsult respect to previous one
This can happen for a couple of different reasons: if the calculations involve random numbers. The random number use might not ...

5 Tage vor | 0

Beantwortet
what is the unit of amplitude in matlab simulink?
The unit of magnitude for sine wave in Simulink is the "Finagle" . https://wiki.c2.com/?FinaglesVariableConstant

5 Tage vor | 0

Beantwortet
How do I fix the error of arrays having incompatible sizes?
Yes, you need to loop over KC values. Your ndt is a vector with values calculated in terms of KC. And that means that X(1:floo...

6 Tage vor | 1

Beantwortet
Please help with fsolve, i keep getting this error
Your posted code has Q0 = [120;21;24;23]; which is fine. But your error message is from running some other code -- code that...

6 Tage vor | 0

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