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Walter Roberson


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45,724 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
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)...

33 minutes 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 ...

1 hour ago | 1

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...

1 hour ago | 0

| accepted

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 hours ago | 0

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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 hours 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 hours ago | 1

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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 hours 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...

3 hours 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) = []...

3 hours 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)...

4 hours 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...

12 hours ago | 0

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

16 hours 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)...

16 hours 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...

17 hours ago | 1

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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; (...

17 hours ago | 0

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Answered
how to split a string
If the current vector is shorter than N or exactly N then add the complete current vector to the end of the cell array and retur...

18 hours ago | 0

Answered
To create a code that differentiate any function
fun = str2sym(input('fun= ', 's')); var = str2sym(input('which variable= ', 's')); y = diff(fun, var)

23 hours ago | 0

Answered
Pulling data from a for loop
T = 29; % %C Tambient = 20; % C Tfilm = (T + Tambient)/2; Tskin = nan; for t = 1:1:100 k_air_2 = (2.4131 + 0.0078 * T)...

1 day ago | 2

Answered
How to get the mean of the function?
Mean of function F over A to B is (integral of F from A to B)/(B-A)

1 day ago | 0

Answered
Best way to solve my implicit equation
In an interactive session: syms any of the names corresponding to variables you will need to change. Calculate lhs(eqn)-rhs(e...

1 day ago | 0

Answered
real simple -- spreadsheet parsing
You can use extractBetween() on the string array, and double() the result

1 day ago | 0

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Answered
merge txt and num back again.
If you must use xlsread() then use the third output of xlsread(), often known as raw, which will be a cell in which each entry t...

1 day ago | 0

Answered
functions of funtions symbolic
You cannot do that, unfortunately. symbolic functions at the MATLAB level are strictly created by evaluating a symbolic express...

1 day ago | 0

Answered
Saving and loading structural array has different format
results_loaded.results = [results_loaded.results;add]; save('results.mat', '-struct', 'results_loaded');

2 days ago | 0

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Answered
How to divide vector to matrix(same row and column)
If you have the Communications Systems Toolbox, then buffer(TheVector, ceil(sqrt(numel(TheVector))))

2 days ago | 0

Answered
Updating UI figures opened during script: uifigure callback works when figure is opened from command line but not if opened from inside of a script
data = guidata(gcf); That is a callback for use with GUIDE, not for use with uifigure (which is App Designer.) 'data = guidata...

2 days ago | 0

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Answered
regionprops( aImage, 'Centroid', 'Image' ) vs regionprops( aImage, 'Centroid' );
Each option to regionprops() tells it another property to measure and return https://www.mathworks.com/help/images/ref/regionpr...

2 days ago | 0

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Answered
imread() wrong gray values
The image file is not RGB, it is an colormapped image. [img,cmap] = imread('image.png'); RGB = ind2rgb(img,cmap); imshow(RGB)...

2 days ago | 0

Answered
defining a polygon area within an array
If you have the Computer Vision Toolbox, then you can use https://www.mathworks.com/help/vision/ref/insertshape.html#btppvxj-1-s...

2 days ago | 0

Answered
Curve Fitting with erfc
I was able to track this down. What is happening is that cftool likes to draw the smooth line, from before the start of the x d...

2 days ago | 0

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