# Ameer Hamza

### Hong Kong Polytechnic University

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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...

ungefär 3 år ago | 1

| accepted

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...

ungefär 3 år ago | 3

| accepted

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')

ungefär 3 år ago | 0

| accepted

append sections of column by n rows to subsequent column

You can use reshape() v; % 1032x1 vector M = reshape(v, 43, [])

mer än 3 år ago | 0

Please Help Optimization using PSO

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

mer än 3 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)

mer än 3 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;

mer än 3 år ago | 0

| accepted

matrix arithmetic numbers short way

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

mer än 3 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 =...

mer än 3 år ago | 0

obtaining large numbers while using syms

Specify the number of digits in vpa() to vpa(x, 4)

mer än 3 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...

mer än 3 år ago | 0

| accepted

How can increase a binary image in size by padding ?

See padarray(): https://www.mathworks.com/help/images/ref/padarray.html For example im = imread('https://www.mathworks.com/ma...

mer än 3 år ago | 0

| accepted

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...

mer än 3 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.

mer än 3 år ago | 1

| accepted

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; ...

mer än 3 år ago | 0

| accepted

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 ...

mer än 3 år ago | 0

| accepted

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...

mer än 3 år ago | 0

| accepted

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...

mer än 3 år ago | 2

| accepted

Placing data in a matrix

Directly use reshape() B = reshape(A, [36 353]).'

mer än 3 år ago | 0

| accepted

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...

mer än 3 år ago | 0

| accepted

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 ...

mer än 3 år ago | 0

| accepted

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)];...

mer än 3 år ago | 0

| accepted

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...

mer än 3 år ago | 1

| accepted

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...

mer än 3 år ago | 0

| accepted

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...

mer än 3 år ago | 0

| accepted

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 ...

mer än 3 år ago | 1

| accepted

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 = ...

mer än 3 år ago | 1

| accepted

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...

mer än 3 år ago | 1

| accepted

separet value in one colone to many colone

Try this mtx= [1 101; 2 011; 3 111; 4 110; 5 110]; cols = reshape(sprintf('%03d', mtx(:,2)), 3...

mer än 3 år ago | 1

How to perform high-precision fitting of points on unknown trajectories? And calculate the fitting coefficient.

If you don't have the equation, then use a non-parametric curve fitting: https://www.mathworks.com/help/curvefit/nonparametric-f...

mer än 3 år ago | 0

| accepted