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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 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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Answered
How to compute the following questions
You can use nnz(BooleanArray) or sum(BooleanArray) to get the number of selected results.

ungefär en timme ago | 0

Answered
"Undefined variable" error even though variable is defined
if frame1 == 1 Background1 = thisFrame1; else This does not define Background1 if frame1 ~= 1

ungefär 9 timmar ago | 0

Answered
How do I prevent the command that caused an error being displayed in the command line?
./my_executable xyz: Signal 127 That indicates that ./my_executable could not be found. You are not in the directory you though...

ungefär 14 timmar ago | 0

Answered
How to create this table/matrix?
ForecastInfo = table(CIV.SYMBOL(1:10,:), ForecastDates', 'VariableNames', {'Symbol', 'Forcecast Dates'});

en dag ago | 0

| accepted

Answered
str2sym error
Work around: symfun('force(t)', sym('t')) or syms force(t)

en dag ago | 0

Answered
writetable or dlmwrite to save an array as a txt file
M = [ 1.0000 -26.2000 -31.7000 2.0000 -27.1000 -33.9000 3.0000 -25.5000 -30.2000 4.0000 -24.4000 -30...

en dag ago | 0

Answered
I keep getting the error message that the variables must be of data type double and it is currently of type sym.
%I'm unsure how else to run this code to solve the 10 eqn system where %the answer comes out in the correct form, please help ...

en dag ago | 1

| accepted

Answered
Hi, this is my code, I want to fit 36 graphs in one graph (36 rays in layout view)
N = 2048; L = 1e4; dx = 4e-3; [x0,y0] = meshgrid((-N/2:N/2-1)*dx); [xL,yL] = meshgrid((-N/2:N/2-1)*dx); [fx,fy] = meshgrid(...

en dag ago | 1

Answered
Genetic algorithm gives same result everytime
You have a single variable that is integer constrained between 10 and 100. That is only 91 different values to search, at most -...

en dag ago | 0

| accepted

Answered
How can I displace x and/or y axes from existing positions?
There is no provided way to do this. You will have to turn axes off, and draw the axes yourself.

2 dagar ago | 0

Answered
Fastest possible prime number detection without using break or return
The fastest possible way of doing any computation depends upon the fine details of your CPU, and upon the fine details of how me...

2 dagar ago | 0

Answered
Processing Multiple Files at once.
[filelist,pathn] = uigetfile('*.*','Please Select a Par File in .dat or .txt', 'multiselect', 'on'); if isnumeric(filelist); er...

2 dagar ago | 0

| accepted

Answered
Uploading .mat files that contain nested structs into a datastore
data = matfile(filename, variables{1}); That is the wrong way to use matfile. The proper way to use matfile is matObj ...

2 dagar ago | 0

Answered
How can I skip the rest of an if statement?
if n > 1 while true if a == 1 disp('Haha') break % (Here is where I want to skip the res...

3 dagar ago | 0

| accepted

Answered
ginput error in matlab 2020a
Error in contains (line 36) tf = ~cellfun(@isempty, strfind(s, pattern)); ... Except that contains is a built-in function and ...

3 dagar ago | 0

Answered
How to determine if angles match
You would get that behavior if prec1 or prec2 are non-scalar and it does not happen that all of the values pass the tests.

3 dagar ago | 0

| accepted

Answered
How to run a function in app designer?
psi = app.EditField_psi.Value; phi = app.EditField_phi.Value; theta = app.EditField_theta.Value; m = app.EditField_m.Value; ...

3 dagar ago | 0

Answered
No sound when playing movie in Matlab2020b
%dispMoviesMatlab - ComputerVision Toolbox audiopath = 'C:\Users\maxab\OneDrive\Desktop\Masters\Experiment\Movies\Chosen'; m...

4 dagar ago | 0

Answered
Where is Shader graphics available in MATLAB
The only access is shading (not very extensive)

4 dagar ago | 0

Answered
vectorized operations on symbolic functions
syms x1 x2 x3; % symbolic variables y = x1^3/3 + x2^2/2 - x3; % symbolic function y X = rand(500,3); % each row representing a...

4 dagar ago | 0

Answered
Slice command for terrain
No. Your data cannot be sliced. Perhaps you might want to contour() the data, and get back the contour matrix, and use somethin...

4 dagar ago | 0

| accepted

Answered
Extract color map from png apply to grayscale image
Use rgb2ind() on the colored image, and take the second output as being the color map. [~, cmap] = rgb2ind(TheColoredImage); i...

4 dagar ago | 1

| accepted

Answered
how to perform a multi variable optimization on matlab
There are several different minimizers possible. Everything except fzero() -- fzero() is restricted to one variable. The trick ...

4 dagar ago | 0

Answered
Binary GA returns floating point numbers
% Set seed for reproducability rng(42); % Load data and define arrays data = readmatrix('Data/File_S1.xlsx'); X = data(2:e...

4 dagar ago | 0

Answered
line search minimization problem, error sym is not convertible to double
f = 316.2*(X1^0.5) + 34.3*X2 + (10^8)*(X1^(-0.5))*(1/X2) %symbolic expression %... A=diff(f,X1) B=diff(f,X2) %A1...

5 dagar ago | 0

| accepted

Answered
Create a list of list and take the mean
cellfun(@mean, aps)

5 dagar ago | 1

Answered
Unregcognized function or variable 'xotold'
if f2<f1 && f2<f3, xoptold = x2; end You only set xtoptold if that condition is true, but later you use it even if the co...

5 dagar ago | 0

Answered
Find data from files that are too large to read in
Use buffer-fulls of data for increased efficiency. fread() a block of data of fixed size. Scan backwards through the block look...

6 dagar ago | 0

Answered
How do I add transparency to a plot in the Live Editor?
Unfortunately, the hack of using a 4-element Color does not work in LiveScript. The work-around is to set the figure Visible pr...

6 dagar ago | 1

Answered
x axis labels not properly working
You used xticks([-0.8:0.4:0.8]); Instead of xticks([-0.08:0.04:0.08]);

7 dagar ago | 1

| accepted

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