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Walter Roberson


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45 739 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
Dot indexing is not supported for variables of this type.
I suspect that the other files do not start with a numeric line before the column headers. I recommend switching to readtable()...

ungefär 5 timmar ago | 0

Answered
Making a complex plot more efficient: is it possible to directly transform a subplot in a image?
I’m wondering if there is a way instead of plotting (exportgraphics is not part of my version) the figure to directly transform ...

ungefär 6 timmar ago | 0

| accepted

Answered
I need an error message if fmincon converges out of constraints
https://www.mathworks.com/help/optim/ug/fmincon.html#busog7r-exitflag Exit flag -2 "No feasible point was found." implies that...

ungefär 6 timmar ago | 0

Answered
Using IF condition with ODE
You need to use Events in the options to terminate the ode integration, and then restart from that time. None of the ode* functi...

ungefär 6 timmar ago | 0

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Answered
fmincon - Index Exceeds Matrix Dimensions
stread = textscan(st, '%s %f %d %d'); % textscan is reading formatted data from text file or string nd = [nd; s...

ungefär 7 timmar ago | 0

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Answered
i am unable to export parallel coordinate and save as jpg in classifier lerner app and also unable to get box of wavetype in export model
Just above the word "model 1" in your plot, notice there is a toolbar entry labeled Export with a downward arrow. Click on that ...

ungefär 8 timmar ago | 0

Answered
matlabFunction on symbolic experssion and the Error using symengine
It appears to be a bug. I might look into the internal code when I am more awake, but that code is difficult to read and debug. ...

ungefär 13 timmar ago | 0

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Answered
Populating a large struct
Do not name the variable struct as, that conflicts with the struct call. Preallocate TheStruct(x) = struct('values', [])...

ungefär 21 timmar ago | 0

Answered
How to work around the precision problem?
I worked through symbolically. Suppose that you create your x vector, starting at 0, and that each entry is theoretically perfe...

en dag ago | 0

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Answered
combine or merge multiple excel files into one file.
name = cell(0,0); id = cell(0,0); x2010 = []; x2011 = []; x2012 = []; x2013 = []; x2014 = []; x2015 = []; x2016 = []; x2017 = ...

en dag ago | 0

| accepted

Answered
Solving mach number for 5000 different iterations
%% Equations %p02/p1 ratio p02_p1_6 = p02_6./p1_6; p02_p1_8 = p02_8./p1_8; p02_p1_10 = p02_10./p1_10; p02_p1_12 = p02_12./p...

en dag ago | 0

Answered
Function running slow than scripts when placed in a 'for loop'?
Generally speaking: functions have more opportunities for internal acceleration than scripts have but function calls have over...

en dag ago | 0

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Answered
how to synchronize structures with date fields in text format
dateinfo = cellfun(@(S) datetime({S.date}), C, 'uniform', 0); TT = cellfun(@(S, T) table2timetable(struct2table(S), 'RowTimes',...

en dag ago | 0

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Answered
how to obtain anonymous function after derivative ?
syms x df = matlabFunction(diff(f(x), x), 'vars', {x})

en dag ago | 0

Answered
why does matlab tell me that the "chop" command doesn't exist?
MATLAB does not contain any chop() function, unless it is a method for some object that I cannot think of at the moment. Perhap...

2 dagar ago | 0

Answered
Copyfile/ movefile when filenames are not directly available
Assuming that newFolder is the name of a variable that stores the destination folder name: copyfile(flagged(i).name, newFolder)...

2 dagar ago | 0

Answered
How to save a symbolic equation in a txt file?
save('test.mat', 'A', 'a', 'b', 'c'); When you use syms a that is equivalent to a = sym('a'); That calls into the symbolic ...

2 dagar ago | 2

| accepted

Answered
Unable to perform assignment because brace indexing is not supported for variables of this type.
At the bottom of your loop you have data = data{i}; That replaces the cell array data that contains the cell with framegra...

2 dagar ago | 0

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Answered
How to deploy my code on raspberry pi as a standalone?
It is not possible to deploy CNN training to hardware. It is not possible to deploy augmentedImageDatastore to hardware. Your ...

2 dagar ago | 0

| accepted

Answered
Using fsolve function, I want to get only real positive roots.
You cannot constrain range to positive in fsolve(). You can add an option that will cause fsolve() to stop processing if it enc...

2 dagar ago | 1

Answered
How to save a symbolic equation in a txt file?
If you plan to use the expression inside a numeric solver, you should use matlabFunction(), which has the advantage of convertin...

2 dagar ago | 1

Answered
Can't open nii image with MATLAb R2017a
You need to install https://www.mathworks.com/matlabcentral/fileexchange/8797-tools-for-nifti-and-analyze-image Note: as of th...

2 dagar ago | 0

Answered
Solve an equation and get a solution that depends on a variable
syms Nin(t) % Vin = (sign(t - 200/11)/2 + 1/2)*((11*t)/100000 - 1/500) - (11*t)/100000 + 1/500 eq1 = Nin == Constant * Vin; s...

2 dagar ago | 0

Answered
error message"Matrix index is out of range for deletion."
Consider: vector V = [1 2 -3 -4 5] . Task: delete negative elements. for K = 1 : length(V) if V(K) < 0; V(K) = []...

2 dagar ago | 0

Answered
Error using symengine in numerical solver
syms w_r S = vpasolve(0==(1-((length(r_dc_s)^(-0.5))*(chi2inv(0.95,length(mu))))... /(1*sqrt(w_r'*V*w_r)+((length(r_dc_s)...

2 dagar ago | 0

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Answered
Is it possibile combine an RGB image and an IR image in a FOUR-BAND tiff image?
Tiff class can be used. The IR can be placed into Extra Samples. I seem to recall that you can also directly write an array with...

2 dagar ago | 0

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Answered
How should the value of objective function be returned for fmincon?
f = sum((actual(:) - predicted(:)).^2);

2 dagar ago | 0

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Answered
Solving an optimization problem in fmincon with nonlinear constraints
Warning: Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN. > In ode15s (line 589)...

2 dagar ago | 0

Answered
Complex number error (number will be an array)
Inside of [], anywhere that you have an element, followed by whitespace, followed by - or + followed immediately by an element w...

2 dagar ago | 1

| accepted

Answered
vector uses info from itself to grow without for cycle
function A = calculate_A(n) if n == 1 A = 1/2; else A_before = calculate_A(n-1); A = [A_before; (...

2 dagar ago | 0

| accepted

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