MATLAB: How to manipulate arrays

arraysifmanipulatewhile

Hello! I am trying to create a script in which I sort an array in descending order without using any sort function. So far, I came up with this:
A = [2 1 4 3 6 5 8 7 10 9 12 11 14 13 16 15 18 17 20 19];
n = 1;
    while n <= length(A)
        if A(n) < A(n+1)
            tmp = A(n);
            A(n) = A(n+1);
            A(n+1) = tmp;
        end
        n = n +1;
    end
I thought it would be this simple, but it apparently isn't. One of the things I do not know how to do is place a value of one array into a new array, which I feel is vital in a script like this, but I did not know how to do it, so I did not implement it. Any help will be appreciated. Thank you in advance!

Best Answer

Assigning one array to another is like assigning any other variable. Consider the B = A assignment here.
It looks as though you want to do a bubble sort, the simplest sorting algorithm. You’re close. This is how I would do it:
A = [2 1 4 3 6 5 8 7 10 9 12 11 14 13 16 15 18 17 20 19];
B = A;                                                      % Original Vector
swap = true;
while swap
    swap = false;
    for n = 1:length(A)-1
        if A(n) < A(n+1)
            tmp = A(n);
            A(n) = A(n+1);
            A(n+1) = tmp;
            swap = true;
        end
    end
end
The idea is to iterate the swapping loop until the ‘swap’ test is false ( i.e. no swap was made during a particular iteration of the vector ). Your loop sorts in descending order. You can add a counter to keep track of the number of swaps that were made.
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