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Walter Roberson


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46,516 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
Plot Multiple Functions in a single call to fplot
fplot(ax, @(x) [xt(x), yt(x)], [0.390])

14 hours ago | 0

Answered
Could I modify the string position in the"TextScatter3" function ?
XData, YData, and ZData properties together control the positions.

18 hours ago | 0

| accepted

Answered
How do I convolve a transfer function with a rect function?
Use symbolic calculations. The transfer function would be syms s syms t real Pi = sym(pi); f = 1E9; w = 2*pi*f; h = w/(s...

23 hours ago | 1

| accepted

Answered
Format Specifier in textscan
The file contains values that exceed 2^31-1 which is the limit for signed 32 bit integers. If you are required to read into 32 b...

1 day ago | 2

Answered
Reshape data to insert into eeglab
For any one 40 x 12 x 4096 array, permute(TheArray, [2 3 1]) To run through several files, see http://matlab.wikia.com/wiki/FA...

1 day ago | 0

Answered
Is it permissible to re-install a specific older version of MATLAB on an existing license, after having to re-install my Operating System and application software, due to a catastrophic system failure (and, if so, how)?
Yes, you can install any version you have paid for, and any earlier versions as well. (For versions before 2012 you might need t...

1 day ago | 0

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Answered
Add class to Scripts
That cannot be done. Class methods can only be defined inside of .m files whose first executable word is classdef

1 day ago | 0

Answered
Classify requires at least 3 arguments
There are multiple functions named classify() Most of the classify() routines are methods of particular data type, and will on...

2 days ago | 0

Answered
How to take advantage of AWS Ec2 if my code cannot be parallelized?
Edit the cluster profile to increase the number of threads per worker. The parpool size must be reduced by the same proportion. ...

2 days ago | 0

Answered
which kind of license can I use?
Standard individual license, also known as Professional license or Commercial licence (all are the same thing.) None of the o...

3 days ago | 1

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Answered
32bit Compiler options
MATLAB Coder can generate C code that can be compiled by whatever toolchain you want. However MATLAB Coder supports very little ...

3 days ago | 1

Answered
How can I compare two separate images (before and after) and count how many pixels are in a particular spectrum?
Example: RGB=imread('image.jpeg'); figure(1) imshow(RGB) HSV = rgb2hsv(RGB); H = HSV(:,:,1); R = RGB(:,:,1); G = RGB(:,:...

3 days ago | 0

Answered
Trouble with struct indexing?
The best approach is not to do that. http://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be...

3 days ago | 0

Answered
How to merge text files vertically?
projectdir = 'directory files are in'; outdir = 'directory files are to be written to'; %should not be same as projectdir ...

3 days ago | 0

Answered
Normalized to unity by summation
You can use out= ((abs(c0)).^2) + symsum(c,n,1,inf); and that will be faster than for upper bound 100. The symsum() will stay ...

4 days ago | 0

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Answered
How to import to Matlab many text files as table type
projectdir = 'directory the files are in'; dinfo = dir(fullfile(projectdir, '*.txt')); %use appropriate extension filenames ...

4 days ago | 0

Answered
image processing canny edge detection
YourImage = imresize(imread('baby.jpg'), 1/8); R = YourImage(:,:,1); G = YourImage(:,:,2); B = YourImage(:,:,3); ER = ed...

4 days ago | 1

Answered
Use Period Marker to fill circles drawn using viscircles
viscircles draws two lines with the same coordinates but with different line widths (and potentially different colors). This is ...

4 days ago | 0

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Answered
easy question : why i get NaN here ?
J = 0.01; b = 0.0737; K = 0.072; R = 1.17; L = 0.024; syms w temp = K/(w*(((J*w+b)*(L*w+R))+K^2)); tempc = collect(temp...

4 days ago | 1

Answered
adding books to book list
fprintf(fid, '%s %s %s\n', NewCode, NewName, NewGenre) ;

5 days ago | 1

Answered
Error: The variable Calls in a parfor cannot be classified.
%% Place Call Times into corresponding variables CallA = Calls{1}; Earlier you index Calls{i} where i is the parfor ...

5 days ago | 0

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Answered
I kept on getting error that says "Error in port widths or dimensions. 'Output Port 1' of 'simulink_controller/Sum2' is a [2x2] matrix."
Pass the output of the Sum2 block through a Selector block https://www.mathworks.com/help/simulink/slref/selector.html

5 days ago | 0

Answered
Is there a way to change the range function of xlsread based on a variable input?
var = input('enter excel column: ', 's'); variable1 = xlsread('filename.xlsx', sprintf('%s4:%s4', var, var)); variable2 = xlsr...

5 days ago | 0

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Answered
How can i convert 160by1 column vector into 16by145 such that first column contain 1 to 16 and second column 2 to 17 and so on?
If you have the communications toolbox, then you can use temp = buffer(YourVector, 16, 15); out = temp(:,16:end);

5 days ago | 0

Answered
Input Argument for contour must be real
rOD = real(OD_MO(:)); minOD = min(rOD); maxOD = max(rOD); contourf( X,Y, real( OD_MO), linspace( minOD, maxOD, 40), '...

5 days ago | 0

Answered
how to use different columns of a passed matrix for individual time step in an ode
The ode*() routines are variable step solvers that will adjust their timestep as required to meet the integration tolerances. Th...

5 days ago | 0

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Answered
Help with "Dimension 1 is fixed on the left-hand side but varies on the right ([1 x 1] ~= [:? x 1])" error r2018a.
function plantOutput = modIndex(gridVoltage, setPoint) After that line add assert() statements that test that each of the ...

6 days ago | 0

Answered
Evaluate definite integral numerically, where the function is indeterminate
Break the integration up into parts that are piecewise numerically integratable, and add the parts together. Do not, however, ex...

6 days ago | 0

Answered
Passing a matrix as a parameter in ode15s
function dvdx = ode_x(x,vx,vfx) dvdx = reshape(vfx./reshape(vx, size(vfx)) - 1), [], 1); end

6 days ago | 0

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Answered
Is there a non-eval based solution to effectively getting the output of disp as a string value?
You can use diary() to have the output of disp copied to a file, then turn diary off and read the file. This will not be any bet...

6 days ago | 0

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