# Walter Roberson

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.

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**Content Feed**

Error Using Abs matlab function: check for incorrect argument data type or missing argument in call to function 'abs'

abs is not supported for optimization variables. However, sqrt and squaring are supported.

circa 8 ore ago | 0

| accepted

Can MATLAB 2020b run on a Surface Pro X or Pro 8

Yes MATLAB should run on the Pro 8. It will not run on the SQ2, or at least not natively; it certainly would not be supported...

circa 13 ore ago | 0

| accepted

How to convert a sym variable to an ordinary variable?

symbolic variables can be converted to numeric only if they have no unbound variables and all expressions with bound variables (...

circa 13 ore ago | 0

Looping through object array, possible to get an iterator to index into the object array?

When you "for" name=array then matlab iterates over the columns of the array, setting the variable to each column in turn. So tm...

circa 22 ore ago | 0

Why am I not getting output in the combinations of salts field?

You assign string into C and copy that to combination of salts, and then put that as the second entry in the cell. The cell gets...

1 giorno ago | 0

how can i extract A= rand([3.85 9.22],5,1) without getting an error

rand(SIZE) * (UPPER - LOWER) + LOWER

1 giorno ago | 0

Simplifying a symbolic expression

You are trying to find the symbolic roots of a degree 5 polynomial. It does not happen to be one of the quintic polynomials that...

1 giorno ago | 0

How can I change my username?

The first thing to do is run the Deactivation executable that you will find in your MATLAB installation directory. Then, change...

1 giorno ago | 0

Legend for multiple plots varying parameters

% matlab and maple for theta plot for different xi values figure subplot(2,1,1) hold on for ixi = 1:2 xi_part = "xi = "...

1 giorno ago | 0

| accepted

Wcompress for 1D data

but i notice that the size of the data file after and before the wdencmp is the same, What you are writing to the file is the r...

1 giorno ago | 0

How to permute elements of jth column of a matrix iteratively

A=[1,2,3 ; 7,8,9 ; 13,14,15] perms_of_(A) function perms = perms_of_(A) [rows, cols] = size(A); perms = repmat(A, ...

1 giorno ago | 0

Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

Error in cell2mat (line 46) M(i,j) = C{i,j}; That line of code does not exist in Mathworks cell2mat, at least not ...

1 giorno ago | 0

please help me for , create a plot of the two functions sin(1.5x) and cos(2x) from 0 to 4pi

y2=cosd(2x); There are absolutely *no* places in MATLAB that permit implicit multiplication. If you want to multiply two th...

2 giorni ago | 0

Unwanted items showing up in plot legend

Record the handle of all scatter() calls in an array. Pass that array to legend()

2 giorni ago | 0

| accepted

Matlab code for solving nonlinear equations

In the general case that could be difficult and time consuming. For example the nonlinear system might be describing Elliptic Cu...

2 giorni ago | 0

How to solve differential equation including derivative of eigenvalue of tensor?

You need to construct the formula for the eigenvalues of the derivative based on the equation for A. As you have a 3x3 matrix th...

2 giorni ago | 1

Using regexp to parse plot's LineSpec

Shapes and colors in linespec may be given in full or in any leading prefix of the word, and the parts can be run together with ...

2 giorni ago | 0

load function: how do you to skip lines in ASCII File that generate errors?

No. load() of a text file is documented as only being guaranteed to work for files saved with save -ascii In practice load() ...

2 giorni ago | 0

Problem in evaluating the value of the derivative of multivariable function

matlabFunction(diff(f1, x), 'vars', [x, y] )

2 giorni ago | 0

| accepted

Symbolic Sum to find a general expression for arbitrary n terms and arbitrary variable definitions

You cannot do that in MATLAB for symbolic limits. For specific limit, n being a given positive integer, then you would not us...

2 giorni ago | 0

initialize complex values in column vector

Suppose that you had coded [1 0 -1] then how many values would you expect as a result? Is that to be interpreted as ([(1...

2 giorni ago | 0

why a message about license is show every time i run MATLAB"??

The message appears every time you start MATLAB because if it only appeared every second or third time you started MATLAB then y...

2 giorni ago | 0

abs function equivalent in c++

https://cplusplus.com/reference/cstdlib/abs/ In C++ abs() is overloaded and for double precision will call fabs() fabs() w...

3 giorni ago | 0

How to use three differential equation in pplane in Matlab?

dfield is for one differential equation, pplane is for two differential equations, for studying phase planes. The software is...

3 giorni ago | 0

replace diff function with for loop and if structures

Using if structures is pretty useless there. The calculation is very straight forward, and the only relevant questions are: do ...

3 giorni ago | 0

Consider particle “P” having random walk in 1-D, Let N steps of equal length be taken along a line.

Encode a step to the left as binary 0. Encode a step to the right as binary 1. Any particular random walk of N steps can then be...

3 giorni ago | 0

How could i merge spectrograms ??

No, it is not possible to merge spectrogram(); see the technical discussion at https://www.mathworks.com/matlabcentral/answers/1...

3 giorni ago | 0

Discarding certain values of a variable.

if (Hs<0.2) | (Hs>0.5) Hs=0; else Hs = [Hs 4*sqrt(sum(sum(s)))]; end In the first condition...

3 giorni ago | 1

Any comment to speed up the speed of caculation of symbolic loops having Legendre polynomials?

Wxy2(r) = W(i, j, 2, r)*legendreP(i, zeta__2)*legendreP(j, eta__2)*q(r, 1) + Wxy2(r); Wxy3(r) =...

3 giorni ago | 1

| accepted

How to store values in a matrix?

for theta = 0:5:90 R = [cos(theta) (-sin(theta)) 0; sin(theta) cos(theta) 0; 0 0 1]; end That is not creating one R f...

3 giorni ago | 0