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Walter Roberson


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47.684 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
sacar la primera, segunda, tercera y cuarta derivada de una función
You just keep going. After Derivada=diff(f,x,1); you can segunda = diff(Derivada, x); tercera = diff(segunda, x);

alrededor de 3 horas ago | 0

Answered
How to resize array using a mask
a(logical(cell2mat(mask)),:)

alrededor de 3 horas ago | 0

Answered
Student version running on different OS and machine at a time
can I install and run Matlab on the same computer but under different OS? Since this is a dual boot machine, it will be one OS a...

alrededor de 3 horas ago | 0

Answered
Skip specific line from a text file
If you use fopen / textscan / fclose, then you can specify 'commentstyle', 'e r r' . That tells it to skip from 'e r r' to the e...

alrededor de 3 horas ago | 0

Answered
Files missing from a folder
for K = 1 : 2041 thisfile = sprintf('%d.txt', K); if ~exist(thisfile, 'file'); continue; end %file exists, proces...

alrededor de 3 horas ago | 0

Answered
Will Matlab mldivide( \ ) operator use all the available cores when used on multi-node?
It will use up to the current maxNumCompThreads https://www.mathworks.com/help/matlab/ref/maxnumcompthreads.html The number of...

alrededor de 4 horas ago | 0

Answered
surrogateopt: Dot indexing is not supported for variables of this type.
Removing the -nojvm solves the problem (for reasons currently unknown.)

alrededor de 7 horas ago | 1

| accepted

Answered
Numerical integration of symbolic equation
This is impossible to do as a numeric integration.

alrededor de 13 horas ago | 0

Answered
specifying the horizontal linetype '_' produces an error.
https://www.mathworks.com/help/matlab/ref/linespec.html horizontal line style is '-' not '_'

alrededor de 13 horas ago | 0

Answered
Solve Function Doesn't Give The Solutions
Warning: Solutions are parameterized by the symbols: x. To include parameters and conditions in the solution, specify the There...

alrededor de 20 horas ago | 0

Answered
Unrecognized function or variable when reading an excel file.
When you have if expression then MATLAB considers the condition to be true only if all values of the expression are non-zero. Y...

alrededor de 20 horas ago | 1

Answered
Symbolic parameters not supported in nonpolynomial equations
vpasolve() has two different execution modes. If the system of equations is polynomial in all of the variables, then vpasolve()...

alrededor de 21 horas ago | 0

Answered
reading file in matlab
The code is intended to read binary files containing quadrature data. The code reads the entire file as a series of uint8 value...

alrededor de 21 horas ago | 0

Answered
adding functions to path
The first line is a comment. The second file picks out the full name of the file that contains the executing code (mfilename('f...

alrededor de 21 horas ago | 0

Answered
How to assign the number of filled columns of a text file as the value of a variable
detectImportOptions() might be your easiest method. Otherwise, fid = fopen('E:\A\nt.txt'); while true thisline = fgetl(fi...

alrededor de 22 horas ago | 0

Answered
Save figure with a specific name
[filedir, basename, ext] = fileparts(filename); newname = fullfile(filedir, [basename '.png']); saveas(h, newname, 'png');

alrededor de 22 horas ago | 1

| accepted

Answered
I got an error as symbolic function expected 3 inputs and received 1 in the line no 5 (g1{r}(u)=g1{r}(u)+(u{i}-u1(i))./5*chebyshevT(i-1,2*x(r)-1)). How can I fix that?
m = 3; x = rand(1,m-1); %replace with your actual data, which must be at least m-1 long v = rand(1,m+1); %replace with you...

1 día ago | 0

| accepted

Answered
How to Import/parse sparse data from a text file into MATLAB?
S=fileread('test.txt') ; data = str2double(regexp(S, '-?\d+(\.\d*)?, 'match' ) ; This code allows for negative data eve...

1 día ago | 0

Answered
I want to plot power of helicopters on y axis and name of helicopters on x axix.please help
categorical() the cell array of character vectors that are the helicopter names, and then plot() providing the categorical varia...

1 día ago | 0

| accepted

Answered
error with indices and vectors
MATLAB has no implied multiplication. A(1+i/12) is syntactically always either a request to execute a function indicated by A w...

1 día ago | 0

| accepted

Answered
How to resolve an error for forward substitution code?
m=[0.6000; 0.3704; 0.1311; 0.2629]; %sub diagonal of lower triangular matrix of A That is a column vector, one column. c(i)=b(...

1 día ago | 0

| accepted

Answered
What is "l"?
No, l did not have any special meaning. Is it possible that this is a nested function? Was there an end statement after what yo...

1 día ago | 0

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Answered
How to use an array as an input in a while loop
Your question requires that you plot with t2 as the independent variable and R4 as the dependent variable. You are currently lo...

1 día ago | 0

Answered
How to only change part of the background color?
set(gca, 'color', [1,1,1]) %instead of gcf

1 día ago | 0

| accepted

Answered
For and while loop problem
while T(i) > T(i+1) Sd(i) = cp*T(i)+ g*h(i); end Whenever you have a while loop, the condition is tested first, and if t...

1 día ago | 0

Answered
What is the use of /begin...../end in regex?
The / character and "begin" and "end" have no special significance in regexp: they are just plain text characters. Which is to...

2 días ago | 0

Answered
fmincon optimization with nonlinear constraint
nonlcon = @(x) deal([], x(1)-x(3)-(x(2)-x(4))) However, you should consider rewriting with one fewer variable. x(1)-x(3)=x(2)...

2 días ago | 0

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Answered
How to extract input variable name when calling to GUI (GUIDE) function?
Don't Do It. But since you seem unlikely to understand that you have made a design mistake until you have had enough complaints...

2 días ago | 0

| accepted

Answered
Is Mac an option for working MATLAB?
The new (2020) MacBook Air with i5 processor has quad-core 1.1 GHz base rate with turbo boost to 3.5 GHz. Turbo boost is used ...

2 días ago | 2

| accepted

Answered
making picture through imshow
Z = logical(256,256); Z([1:16,end-15:end], :) = true; Z(:, [1:16,end-15:end]) = true; You should be able to continue from the...

2 días ago | 0

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