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Walter Roberson


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50.041 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
Moving a perpetual license after maintenance expires
Yes, Yes, and Yes.

ongeveer een uur ago | 1

| accepted

Answered
Array in a symsum
You are attempting to index x with a symbolic variable. That is not possible with MATLAB, and that is something that is not expe...

ongeveer 11 uur ago | 0

Answered
How to fix error message "Invalid pfile. The file header is corrupt."
You cannot fix it yourself. You need to get the site to recreate the file. However, it is possible that the p file was create...

ongeveer 14 uur ago | 0

Answered
I am trying to test a part of my code but it shows me this message ! how can i solve it , Help plz !
for k=1:1:lenght(Material) You have not defined any variable named Material but you have defined a variable named material...

ongeveer 15 uur ago | 0

Answered
roots of non linear periodic function
format long g rng(655321) L = randn() P = rand() * 10 C = @(x) x.*L.*tan(x*L)-P root1 = fzero(C, pi/3) N = 10; nroots...

ongeveer 15 uur ago | 0

Answered
evaluation of anonymous function
In that code, V is never evaluated. In that code, MATLAB sees the @(x) (0.5+0.5.*sign(r.^2-x.^2))*V0 part and constructs an ...

ongeveer 15 uur ago | 2

| accepted

Answered
Help with Surrogate Modeling Multivariable Objective Function
Yes, you should be able to do that. Construct lb and ub vectors (mandatory!! and must be finite!) that are length() equal to the...

ongeveer 16 uur ago | 0

Answered
Reduce symbolic fraction by powers of ten
load sample; syms s G = YQ_sym(1,2); vpa(G,5) vpa(simplify(G),5) [N,D] = numden(G); Dc = coeffs(D,s); FN = factor(N);...

ongeveer 16 uur ago | 1

| accepted

Answered
how to get average of multiple rows and subtract from one group of average to another
M = your matrix with 10039 rows and 64 columns N = 30; whole_blocks = floor(size(M,1)/N); leftover = size(M,1) - whole_blocks...

ongeveer 17 uur ago | 0

| accepted

Answered
Normalization of symbolic expression
syms L R K b J s v a1 = det ([(L*s+R) (v); (-K) (0)]); a = det ([(L*s+R) (K); (-K) (J*s+b)]); g=collect((a1/a)*(1/v),s); G=s...

ongeveer 18 uur ago | 0

| accepted

Answered
How can I add multiple 1 x 1 strings to all rows in a table?
https://www.mathworks.com/help/matlab/ref/table.addvars.html You can use 'Before' and 'after' to add the variables into a part...

ongeveer 18 uur ago | 0

Answered
Merge two figures into one
TextFontSize=20; LegendFontSize = 18; set(0,'DefaultAxesFontName','Times',... 'DefaultLineLineWidth',1,... 'DefaultL...

ongeveer 18 uur ago | 0

| accepted

Answered
Putting two FAS figures into one.
Remove the call figure; Add the call hold on after the plotting

ongeveer 19 uur ago | 0

Answered
Automatically load a csv file from a folder
EEGDIR = '/Users/roberson/Plan9/Dhort/ECGData'; tries = 42; found = true; for trynum = 1 : tries random_MaleShortName = ...

ongeveer 19 uur ago | 0

Answered
Displaying a value using fprintf with certain number of decimals.
format long g a = rand*10 fprintf('The answer for a is %.2f m/s\n', a)

ongeveer 19 uur ago | 1

| accepted

Answered
solution of ordinary differential equations when there is a f(t)
I don't know what's C8 and should I just take the (-exp(2*C8 + 2*t)/(exp(2*C8 + 2*t) - 1))^(1/2) as the correct solution? Yes? ...

ongeveer 19 uur ago | 0

| accepted

Answered
Acquire data from smartwatch sensors via USB
That is going to depend in part on the smartwatch. I just tried with an Apple Series 3 smartwatch. The charging cable is a USB-...

ongeveer 19 uur ago | 1

Answered
Problem with code originally written for MATLAB R2006a -- problems with break statement
Long ago, no error message was generated for a break outside of any loop. I never used that behavior myself... I think I encount...

ongeveer 20 uur ago | 0

| accepted

Answered
Finding inverse Laplace when the inverse Laplace function is a piecewise function
rewrite(x, 'piecewise')

ongeveer 20 uur ago | 0

Answered
Rotating a meshgrid in 3D
The 3d process is much the same, except that you build xyz columns and multiply by a 3x3 array. It can be easier to use makeg...

ongeveer 21 uur ago | 0

| accepted

Answered
MEXFILE error, libmex.dylib not loaded
You might need to do DYENV = 'DYLD_LIBRARY_PATH'; olddy = getenv(DYENV); path_to_add = fullfile(matlabroot, 'bin', 'maci64');...

ongeveer 22 uur ago | 0

Answered
hour of datenum type
datetime("now") Okay, creates a datetime object and lets it be displayed month(datetime("now")) Okay, creates a datetime obje...

ongeveer 22 uur ago | 0

| accepted

Answered
How to replace x or y axis tick values with texts
x=[1,3,4,6]; y=[20,40,50,80]; plot(x,y); yticks([20,40,60,80]) yticklabels({'white', '\color{red}red', '\color{green}green', '...

ongeveer 23 uur ago | 0

| accepted

Answered
Solve the following simultaneous set of nonlinear trigonometric equations:
c1 = 0, c2 = 0, c4 = 0, c5 = -1000, c6 = 0, d3 = -500, s1 = 1/1000, s2 = -1, s4 = -1/s6, s5 = 0, s6 = s6 c1 = 0, c2 = 0, c4 =...

ongeveer 24 uur ago | 1

| accepted

Answered
Can you run third party applications multiple times with MATLAB for analysis?
Sometimes it is possible. It depends on the application, on whether it accepts command line arguments; and if you are using MS W...

1 dag ago | 0

Answered
Cannot convert double value 0.01 to a handle.Cannot convert double value 5 to a handle.
format long g fig = figure(1); fig class(fig) %notice it is a handle fig.Number %that has an associated integer H1 ...

1 dag ago | 0

Answered
Unable to perform assignment because the left and right sides have a different number of elements
if 0 <= t(i) && t(i) <= 8 V(i) = 10*t(i).^2-5*t(i); Also else t(i) > 26; That calculates whether t(i) is g...

1 dag ago | 1

| accepted

Answered
pre allocating variables in matlab
That's not what I get. imgThresh = im2bw(imread('image.png')); rows = size(imgThresh,1); columns = size(imgThresh,2); x=...

2 dagen ago | 0

Answered
Printing and Plotting after each loop
A=[1 3 4;3 5 6] U=[] for i=1:10 A = A * 2; U=A; dlmwrite('U.txt', U, '-append') end !cat U.txt

2 dagen ago | 0

Answered
How to check a change in one quantity given a known in a separate but related quantity
format long g A = randi([0.5e10 6e15],1, 100); B = rand(1,100)*6-3; mask = A(2:end)./A(1:end-1) >= 10; Bdiff = diff(B); c...

2 dagen ago | 0

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