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Walter Roberson


Last seen: Today
50.117 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
Error using nargin You can only call nargin/nargout from within a MATLAB function.
nargin cannot be used at the command line, and it cannot be used in a script file or Live Script (except inside a function defin...

alrededor de 2 horas ago | 0

Answered
Random Colour in Drawformattedtext Function in Matlab
DrawformattedText is part of psychtoolbox but not part of MATLAB. cmap = [0 0 1; %blue 1 1 0; %yellow 1 0...

alrededor de 2 horas ago | 0

| accepted

Answered
Finding the mean of a group of images?
bfilter2() is not part of MATLAB, so we do not know what it does. There is a File Exchange contribution https://www.mathworks.co...

alrededor de 2 horas ago | 1

| accepted

Answered
How to save output(.mat) file for all generated values instead of last values ?
function y = opt(x) Kp = x(1); Ki = x(2); disp(x); filename = 'pqfile.mat'; if ~exist(filename) pqsave.x = []; else...

alrededor de 2 horas ago | 0

Answered
Calling function to evaluate another called function - delimeter error
a = wn(@lk,6,10,5)

alrededor de 3 horas ago | 1

| accepted

Answered
Why is 10^(log10(x)) not x?
a = 14.25; a2 = 10^(log10(a)); for K = 1 : 100 a3 = 10^(log10(a+K*eps(a))); if a3 ~= a2; break ;end end fprintf('a...

alrededor de 3 horas ago | 1

Answered
How can I get my matrix to populate with correct values from for loop?
xm = (xa + xb) / 2; You do not reset xa and xb to their original values for each j value.

alrededor de 4 horas ago | 0

Answered
How to remove the unwanted zero at the end in the floating point variable?
And then I want to convert it to binary (only 1.0066 to binary). How can I do that? a=1.006600000000000 bin = int16(a*2^14) r...

alrededor de 4 horas ago | 0

Answered
Input signal and arguments in Ode45. Not enough imput arguments
http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

alrededor de 4 horas ago | 0

Answered
How do I erase following data?
x(find(x<28,1):end) = nan ; or x(~cumprod(x>=28)) = nan;

alrededor de 5 horas ago | 1

| accepted

Answered
Reading in an array using MATLAB Coder
https://www.mathworks.com/matlabcentral/answers/85669-problem-using-emxarray_real_t-from-matlab-coder#answer_95210 Read the d...

alrededor de 5 horas ago | 0

Answered
Problems with plotting/graph
you did a hold on before that, and that would have frozen ylim, so they might be off plot. ylim auto

alrededor de 5 horas ago | 0

Answered
Vertical error bars disappear on logy plot
When you use Yscale log, then: * if *all* of the y coordinates are negative, a warning is given and plotting proceeds as if t...

alrededor de 6 horas ago | 0

Answered
Alternates of polyval and polyfit?
https://en.wikipedia.org/wiki/Vandermonde_matrix Suppose you had a polynomial of degree 2, y = a2*x^2 + a1*x^1 + a0*x^0, a2, a...

alrededor de 7 horas ago | 1

| accepted

Answered
How do I input a matrix into an equation?
http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

alrededor de 8 horas ago | 0

Answered
2 Variables and 2 Unknowns Returning Incorrect Results
fprintf('solution is %g \n', solVA2x) The %i format is only for integers.

alrededor de 8 horas ago | 0

Answered
How do I save multiple .txt files from different folders to one new folder?
filenames = fullfile({fileList.folder}, {filelist.name}); copyfile(filenames, outputPath); This assumes that the source file...

alrededor de 8 horas ago | 0

Answered
How to apply sum function for simulating charges around a circle?
I showed the strategy in https://www.mathworks.com/matlabcentral/answers/766426-how-can-i-handle-division-by-zero-inside-the-sym...

alrededor de 8 horas ago | 0

Answered
Need MATLAB help for assignment
for r = 1:length(R) for b = 1:length(bD) F = (16/3).*(1./bD).*(1./R).^3.*abs(sqrt((1./R).^4-2.*(1./R).^2.*cos(2.*theta)+...

alrededor de 8 horas ago | 0

Answered
Unpacking and tabulating contents of a cell array
all_numbers = horzcat(vsel{:}); This is the same as all_numbers = [vsel{:}];

alrededor de 9 horas ago | 0

| accepted

Answered
Reading data from file
Read one line at a time and sscanf() the line. fid = fopen('datafile.m','r'); x = sscanf(fgetl(fid), '%d'); Remember to fclos...

alrededor de 9 horas ago | 1

| accepted

Answered
Unable to Print Graph being Generated in axes.handle4
You posted that you tried saveas(handles.axes4) but you would need [file,filepath] = uiputfile('*.jpg'); if ~ischar(file); r...

alrededor de 9 horas ago | 0

| accepted

Answered
Undefined function or variable 'chebwin'.
chebwin() needs the Signal Processing Toolbox to be installed and licensed. That is the same toolbox as pwelch, but due to the w...

alrededor de 9 horas ago | 0

| accepted

Answered
How can I change an element in a matrix with the median of itself and its surrounding elements.
https://www.mathworks.com/help/images/ref/medfilt2.html medfilt2() is already part of the Image Processing Toolbox. You can a...

alrededor de 10 horas ago | 0

Answered
Help with function that uses a while statement to get the next largest prime number
isscalar() is a test to see if size() of the argument is all 1's -- not empty, not 2D, just a single element. isscalar() has n...

alrededor de 10 horas ago | 0

Answered
How can i handle division by zero inside the symsum function?
z=symsum((1./((x-k).^2+y.^2)),k,-1,1); That is not worth doing with symsum. It is only 3 terms; just write them out, or use a v...

alrededor de 10 horas ago | 0

Answered
Replace number if within 2 numbers and smaller than last number.
A = [1 15; 20 36; 37 50] B = [8, 42, 100] Select = @(M,idx) M(idx) PW = @(cond,val1,val2) Select([val1,val2], [cond, ~cond]...

alrededor de 11 horas ago | 0

| accepted

Answered
Preserve the order of matrix when doing symbolic matrix multiplication
This is not possible in any released versions. It might be possible in a future version. In all released versions, individual...

alrededor de 12 horas ago | 0

| accepted

Answered
2d plot problem
You need to use separate plots (at least for third). The disadvantage is that it becomes more difficult to track relative values...

alrededor de 12 horas ago | 0

Answered
Root finder solver for cubic equation
syms M1 gamma theta_degrees tanbeta_degrees eqn = 1 + (gamma - 1)/2 * M1.^2 * tand(theta_degrees).*tanbeta_degrees.^3 + (1-M1.^...

alrededor de 12 horas ago | 0

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