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Walter Roberson


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46 482 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
Find Fundamental Frequency to know if it´s a Man or a woman or children
Your project is not possible to complete using any known science. Suppose for example that group A has a mean score on somethin...

ungefär en timme ago | 0

Answered
Why are the results different when calculating a 10 x 3 matrix and a 1 x 3 matrix?
XYZ_rwd21t = [1.30937778204061e-14,-13.8617246105272,22.6275000000000; XYZ_rwt212t(i, 2) = XYZ_rwd21t(1, 2); Okay, so ...

ungefär 3 timmar ago | 0

Answered
fminsearch for ligistic fit
f2 = @(p)f(p,x); That relies on x existing in your workspace. If you are going to do that you might as well assume it on the...

ungefär 13 timmar ago | 0

Answered
Adding elements of a vector in matlab
fliplr( cumsum( fliplr(a) ) )

ungefär 18 timmar ago | 0

| accepted

Answered
Integration from 0 to a variable.
integral() is for numeric integration, but solve() is for symbolic work. fun2=@(x)((s-x).*((b/a).*((x/a).^(b-1)))/(1+((x/a).^...

ungefär 18 timmar ago | 0

Answered
fprintf to plot error
See https://www.mathworks.com/matlabcentral/answers/534868-make-matrix-with-loop#answer_439778 for a general code outline that y...

ungefär 19 timmar ago | 0

Answered
Divide .wav file into equal segments
The below will split all .wav in a given directory into 3 second buffers. A directory named after the file will be created insid...

ungefär 20 timmar ago | 1

| accepted

Answered
How can I make a non uniform quantization of an image?
If you have the Communications toolbox you can use quantiz() https://www.mathworks.com/help/comm/ref/quantiz.html You can also...

en dag ago | 0

Answered
Matlab License for students
MATLAB Online is not free; you need to have an active account of one of several kinds. If Harvard has a Total Academic Headcoun...

en dag ago | 0

Answered
Y axis in scientific form
If you are referring to the scale factor that sometimes get put up near the top of the Y axes, then the answer is that there is ...

en dag ago | 0

Answered
solve vs. fsolve
Sometimes plotting and finding intervals by eye is not productive. In the general case, theory says that it is impossible to c...

2 dagar ago | 0

Answered
Make matrix with loop
In the general case: xvals = [list of x values, does not have to be regularly spaced or even sorted]; numx = length(xvals); y...

2 dagar ago | 0

Answered
Plot Not showing all values
The max value of col2 is only about 20, but the maximum value of col1 is 992008 Near 210 the entries go like 21.4239 21.5239 ...

2 dagar ago | 0

Answered
Multi Threads operation SERIAL PORT in Parallel
That cannot be done with asynchronous serial ports such as RS232 and USB. In order to synchronize reception of data, you need to...

2 dagar ago | 0

Answered
how to insert value of array to other array
horzcat(). [list of values] is also horzcat()

2 dagar ago | 0

| accepted

Answered
What am I missing in this code I am trying to find roots of a System of Equation?
x=x+transpose(eps) That should be subtraction rather than addition.

2 dagar ago | 1

| accepted

Answered
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
inv(j)*f is going to return a column vector. Your original X0 is a row vector. Since R2016b, if you subtract a row vector and a ...

2 dagar ago | 1

Answered
Function that calls another function in LiveScript
Yes, provided that you are using a MATLAB release new enough to support functions in Live Scripts (which you are.) Note that th...

2 dagar ago | 0

Answered
cumulatives of the dynamical system
You currently have a first order differential equation, diff(D,t) == x(t). When you use it with ode45 you would be using a funct...

2 dagar ago | 0

Answered
Efficiently ways to solve for multiple for loops, of which the indices are the parameters of a function
You can do at least part of it in vectorized form. The following deliberately creates random numbers in the same order as if yo...

3 dagar ago | 0

Answered
How do I define an empty table of unknown size?
Sorry, variables that do not exist do not have any datatype. As you add variables to the table, the datatype associated with t...

3 dagar ago | 0

Answered
upper case need help
str=char(mod(double(lower(str))-97+shift,26)+97);

3 dagar ago | 0

| accepted

Answered
Saving and loading matrices with vpa entries with save and load commands is extremely slow
You are correct, this can happen. The slowdown is inside the symbolic engine, when it is asked to convert into a character repre...

3 dagar ago | 0

Answered
How to extract the events which have more than 3 consecutive rows
r=3; how many repeats mask = idx3.' == 2; %row starts = strfind([false mask], [0 ones(1,r)]; stops = strfind([mask, ...

3 dagar ago | 1

| accepted

Answered
Error detected but matlab did not specify the type of error. pls help out
m25 = Mb.*Nb(1-(0.5.*(c4(i)+c4(i+1))))-((1-(0.5.*(c1(i)+c1(i+1)))).*beta1.*(x2(i)+h2.*m12)+(1-c2(i)+c2(i+1)).*beta2.*(x3(i)+h2...

3 dagar ago | 0

Answered
about random number and matrix
R1=a*[0:n-1]; R2=b*[0:n-1]; R2=rand(1, 1, 100000)+R2.'; % add rand to every element in R2 del=R1-R2 ; % "row vector-column ...

3 dagar ago | 0

Answered
Question about hard coding error
Suppose that you are required to build a function f(x,y), and you happen know it will be called with y = 19, but you write the c...

3 dagar ago | 0

Answered
subset the plot for the subset of x range
See isbetween() or use find(date_vector < last_date_to_plot, 1, 'last') in order to find the end of the group. In the special c...

3 dagar ago | 0

Answered
How to read the name of all output argument in function?
In order to do this, you need to use dbstack('-completenames') to find out the name of the file that you were called from and th...

3 dagar ago | 0

Answered
function or functions of a single variable
fplot('-exp(-x)+x.^2-2*x+2',[0 1]) As far as fplot() is concerned, e is just another variable, and not the base of the natural ...

3 dagar ago | 1

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