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# Ameer Hamza

### Hong Kong Polytechnic University

Last seen: 4 månader ago Active since 2016

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Deleting Specific elemnts from Vector?
If i, j, and k are positive integers, then tm(m) = [] Read about indexing: https://www.mathworks.com/company/newsletters/artic...

nästan 2 år ago | 0

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how to work with variables with different names in a loop?
It is never a good idea to create a variable name like this: A1, A2, ..., AN. Read here: https://www.mathworks.com/matlabcentral...

nästan 2 år ago | 2

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Addition of numbers in array
This is one way x = [7 4 6]; y = [1 4 4]; z = sscanf(sprintf('%d',x),'%d')+sscanf(sprintf('%d',y),'%d')

nästan 2 år ago | 0

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append sections of column by n rows to subsequent column
You can use reshape() v; % 1032x1 vector M = reshape(v, 43, [])

ungefär 2 år ago | 0

Check the code of this FEX package: https://www.mathworks.com/matlabcentral/fileexchange/75101-non-linear-equality-and-inequalit...

ungefär 2 år ago | 0

How can I find distances between 100 points such that I have a set of distances of each point from rest of the points.
Just use pdist() function X = [..]; % create 100x3 matrix dists = pdist(X)

ungefär 2 år ago | 1

Binary value convert.
Read about logical indexing A = [0 1 0 1;1 0 0 1; 0 0 0 1; 1 0 0 1]; A(A==0) = -1;

ungefär 2 år ago | 0

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matrix arithmetic numbers short way
Yes, quite easily. A = 1:30; Read about colon operator: https://www.mathworks.com/help/matlab/ref/colon.html

ungefär 2 år ago | 0

Change the sign of column of imported file in matlab.
Something like this M_new = M.*[-1 1]; % change sign of 1st column M_new = M.*[1 -1]; % change sign of 2nd column or M_new =...

ungefär 2 år ago | 0

obtaining large numbers while using syms
Specify the number of digits in vpa() to vpa(x, 4)

ungefär 2 år ago | 0

Consider preallocating for speed
It is not an error message; it is just a warning. Pre-allocation helps make the code faster. Read my answer here to get a genera...

ungefär 2 år ago | 0

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How can increase a binary image in size by padding ?

ungefär 2 år ago | 0

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finding all roots of a trignometric equation
range of tan(x) is (-inf inf), so this equation has an infinite number of solutions. Also, the solutions to this equation cannot...

ungefär 2 år ago | 0

Add elements to a matrix
Use repelem() A = [1 2 3; 4 5 6; 7 8 9] B = repelem(A, 1, 2) Note: In MATLAB [ ] are used to create arrays.

ungefär 2 år ago | 1

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Logical Indexing Within a Symbolic Array
Try this syms w1 w2 w3 w4 w5 w6 w7 w8 w9 w10 A = [0 0 0 w7 0 0; 0 0 0 0 w9 0; 0 w3 0 0 0 0; 0 0 w5 0 0 0; ...

ungefär 2 år ago | 0

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How do I replace elements in a vector with other vectors?
Don't create variable name dynamically like rectColor1, rectColor2, .. It always makes code more difficult. Following shows how ...

ungefär 2 år ago | 0

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Read STL FILE on MATLAB
No, this is not how a function is called in MATLAB. Read here: https://www.mathworks.com/help/matlab/matlab_prog/create-function...

ungefär 2 år ago | 0

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Difference between datetime values in minutes
Try this col = minutes([all_combined_short{:,1}].'-all_combined_short{1,1})+1; all_combined_short = [num2cell(col), all_combin...

ungefär 2 år ago | 2

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Placing data in a matrix
Directly use reshape() B = reshape(A, [36 353]).'

ungefär 2 år ago | 0

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How to generating surface without plotting?
Since it is a graphical object, you cannot create it without plotting somewhere. However, you can make the figure invisible so t...

ungefär 2 år ago | 0

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Calculate mean value from different matrices
How are 5 matrices available? Is it a cell array? Try something like this C = {M1, M2, M3, M4, M5}; M = cat(3, C{:}); M_mean ...

ungefär 2 år ago | 0

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Create function such that for each element of the vector it applies different function
Try something like this a = 1; b = 1; x = [2; 4]; f1 = @(x) a*x(1) + 1; f2 = @(x) b*x(2) - 1; F = @(x) [f1(x); f2(x)];...

ungefär 2 år ago | 0

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call function for each combination of rows in A and columns in B
Try this Xtrain = [1 2; 3 4; 5 6]; Xtest = [7 8 ; 9 10]; kernel = @(x1,x2) norm(x1 - x2); m = size(Xtrain, 1); n = size(X...

ungefär 2 år ago | 1

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caxis equivalent for slice plot
caxis() also works for slice(). See the difference between two figures [X,Y,Z] = meshgrid(-2:.2:2); V = X.*exp(-X.^2-Y.^2-Z.^2...

ungefär 2 år ago | 0

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How do i make this code as simple as possible? :(
First, naming variables like final_1, final_2, ... is a bad coding practise: https://www.mathworks.com/matlabcentral/answers/304...

ungefär 2 år ago | 0

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Taylor expansion calculation of exp(x^2)
The formula for taylor series is correct. Just increase the number of terms. x = -3.0:0.1:3.0; N = 12; Taylor_p2 = 0; for n ...

ungefär 2 år ago | 1

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Outputing a correspond element of another variable
Try this A = ["Bayo" "Tun" "s"]; B = [21, 45, 11]; [~, idx] = max(B); output = A(idx); Result >> output output = ...

ungefär 2 år ago | 1

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How can I interpolate a datetime data series to have an interval of 1 minute in MATLAB?
Try something like this T = readtable('sample.xlsx'); [grps, unique_mmsi] = findgroups(T.mmsi); tts = splitapply(@(la,lo,da...

ungefär 2 år ago | 1

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