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Walter Roberson


44.641 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
How do I get a symbolic differentiation of cfit/sfit functions?
When sf is the fit object, f = subs(str2sym(formula(sf)),coeffnames(sf),num2cell(coeffvalues(sf).')); vars = sym(indepnames(sf...

alrededor de 2 horas ago | 0

Answered
Error - Index in position 1 is invalid. Array indices must be positive integers or logical values.
for i = 1:10; The first time through the loop, i will be assigned the value 1 Y=abs(atan((A(i-1,2)-A(i,2)/2000))); The fi...

alrededor de 6 horas ago | 0

Answered
why values of multiwavlet transform have larger values of input?
The simplest wavelet predicts +1 for the first half and -1 for the second half. Suppose you had an input that was [64 64 64 64]...

alrededor de 6 horas ago | 0

Answered
i want to find the solution to an equation containing bessel function x*besselj(1,x)-C*besselj(0,x). I am using newton raphson method but I am getting NaN as the root.
x(1) is 0. besselj(1,0) is 0 and Bi*0 is 0. besslj(0,0) is 1, but you multiply that by x(1) which is 0. So your denominator of y...

alrededor de 7 horas ago | 0

Answered
How to write this loop?
%% readDataFromFile and WriteDataToFile are given functions %% stress.out is a file containing a matrix of 195 elements fu...

alrededor de 7 horas ago | 0

Answered
direct convert to float64 from the data of output of fread
swapbytes(typecast(uint8(data),'double'))

alrededor de 8 horas ago | 0

| accepted

Answered
extract the words from audio file
part1=p1(1:floor(q*1.5),:); part2=p1(ceil(1.5*q):floor(q*2.5), :); part3=p1(ceil(2.5*q):floor(q*3),end, :);

alrededor de 9 horas ago | 0

Answered
Find the solution to the differential equation
N(t) = 1.5x^2 -2x +3 That equation does not reflect your original question dy/dx = 1.5x^2 -2x +3 . The difference is in the var...

alrededor de 9 horas ago | 0

| accepted

Answered
How to add different size arrays to existing graph
fig = openfig('SolarIrradiance.fig'); existing_line = findobj(fig, 'type', 'line'); ax = ancestor(existing_line, 'axes'); lam...

alrededor de 10 horas ago | 0

Answered
Using Accumarray with @maxk instead of @max?
accumarray(a(:,1), max(b,c), [], @(v) mean(maxk(v,3)), 0, true) %final parameter is sparse flag

alrededor de 10 horas ago | 0

Answered
How to read information from a .txt file and convert it into a matrix
S = fileread('frotatego'); info_struct = regexp(S, '^(?<name>.*?)\s+(?<val1>\d+\.\d\d)\s+(?<val2>\d+\.\d\d)\s*$', 'names', 'dot...

alrededor de 10 horas ago | 0

Answered
How to let a numerical field to be assigned preferrentially by user input?
Just always fetch the current version of the field; if the user hasn't modified the values since the last time then they will be...

alrededor de 11 horas ago | 0

Answered
Finding the distance between a large group of points from a plane
https://www.mathworks.com/help/stats/knnsearch.html knnsearch() between the wall points and the cloud points. This does not co...

alrededor de 11 horas ago | 0

Answered
Chaotic bit stream cipher
Logicists maps can be used for this purposes, as they only need to know the current state. "cat map" on the other hand requires...

alrededor de 11 horas ago | 0

Answered
Which interpolation method is best?
Use https://www.mathworks.com/help/matlab/ref/fillmissing.html#bva1z1c-method fillmissing() -- it supports all of the methods yo...

alrededor de 12 horas ago | 0

Answered
How to read and process a text file?
S = fileread('sample.txt'); S = regexprep(S, {'^\$.*?\n', '\r'}, {'', ''}, 'lineanchors'); all_ids = string(regexp(S, '^\S*', ...

alrededor de 12 horas ago | 0

Answered
Every time during the starting of MATLAB these two warnings pop up?
https://www.mathworks.com/matlabcentral/answers/472134-gtk-message-10-32-31-466-failed-to-load-module-canberra-gtk-module

alrededor de 24 horas ago | 0

Answered
jetson function package not found
https://www.mathworks.com/help/supportpkg/nvidia/ref/jetson.jetson.html GPU Coder Support For Nvidia GPU is the required supp...

alrededor de 24 horas ago | 0

Answered
Multiple print outside of loop
Your c is a vector because of the rand(100, 1) None of the code is expecting a vector for c. Note that if you are trying t...

1 día ago | 0

| accepted

Answered
my code doesnt show a graph even if i use the plot command
sinoaz=-23.45*(pi/180)*cos(((2*pi)/365)*(10+n)); Should use n_days instead of n A=asind(sinAz); Should be A(...

1 día ago | 0

Answered
Image Write in Excel
https://answers.microsoft.com/en-us/msoffice/forum/all/what-is-the-maximum-number-of-columns-in-a/5a053135-4865-e011-8dfc-68b599...

1 día ago | 0

Answered
coswm should have a 1x365 dimension, but its dimension is 1x1, what am i doing wrong?
The / operator is Matrix Right Divide, which is least squares fitting effectively. If you did not intend to do fitting at that p...

1 día ago | 0

| accepted

Answered
How can I know if my laptop is plugged into AC power via Matlab?
<https://stackoverflow.com/questions/21249419/how-do-i-programatically-detect-if-my-laptop-is-plugged-in-or-not-osx> You can ...

1 día ago | 0

Answered
I have MatlabR2019b and I am trying to do a simple plot. I am not able to plot anything unless I use scatter(x,y) or area(x,y). How could I get plot(x,y) to work? I am using a Mac.
You need to rename plot.m in the untitled folder directory as it is overriding the Mathworks plot call

2 días ago | 1

| accepted

Answered
Error Message Using ODE45
The part starting from [t,y] = ode45(@vdp1,[0 20],[2; 0]); plot(t,y(:,1),'-o',t,y(:,2),'-o') Should be in a differen...

2 días ago | 0

Answered
fsolve to solve 5th order polynomial
You have an equation of the form A=B. Subtract B from both sides giving an equation of the form (A) - (B) = 0. Now you can fsolv...

2 días ago | 1

Answered
How to convert a grey-scale image into a reverse binary image
Rbin = YourImage <= 42;

3 días ago | 0

| accepted

Answered
Using timer, How can I cleanly exit a function execution, when the timer fires in MATLAB?
There are only four ways in MATLAB to force a function to stop executing without its cooperation: quit MATLAB force an out-of-...

3 días ago | 0

Answered
Getting a empty sym 0x1 error when I run this code
[dP,dVg,dVf,dTf,dTg] = solve([eq1,eq2,eq3,eq4,eq5],[dP,dVg,dVf,dTf,dTg])

3 días ago | 0

Answered
Treating input arguments (not paying attention to order of number)
Use name/value pairs, unless there is something inside of the structs that identifies which kind of object it is for, or some ot...

3 días ago | 0

| accepted

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