modify the matrix, rearrangement of elements

I have a matrix a = [2 4 7 11; 7 9 5 54; 2 5 7 9; 12 41 45 21];

How to get the row matrix such that the elements of matrix a are arranged digonally upwards from the left .

For exapmle the row matrix should me [2 7 4 2 9 7 12 5 7 11 41 7 54 45 9 21];

Thanks in advance.

[Stephen23]

a =
     2     4     7    11
     7     9     5    54
     2     5     7     9
    12    41    45    21

The main anti-diagonal has values [12,5,5,11] (from bottom left to top right), but your example output shows the values [...,12,5,7,11,...]: please clarify the correct expected values.

[CHANDRABHAN Singh]

sir, it is ...12, 5, 5,11..... It is a typing mistake. Sorry for this.

Answer 1

[Srivardhan Gadila]

The following code might help you:

sz = size(a);
rowMat = zeros(1,prod(sz));
ind = 1;
for i = 1:sz(1)
    j = 1;
    ii = i;
    while ii>0 && j<=i
        rowMat(ind) = a(ii,j);
        ind = ind+1;
        j = j+1;
        ii = ii-1;
    end
    if i == sz(1)
        for j = 2:sz(2)
            ii = i;
            jj = j;
            while ii>1 && jj<=i
                rowMat(ind) = a(ii,jj);
                ind = ind+1;
                jj = jj+1;
                ii = ii-1;
            end
        end
    end
end
a
rowMat

Refer to MATLAB Onramp to get started with MATLAB.

Answer 2

[Stephen23]

>> a = [2,4,7,11;7,9,5,54;2,5,7,9;12,41,45,21]
a =
     2     4     7    11
     7     9     5    54
     2     5     7     9
    12    41    45    21
>> S = size(a);
>> V = 1-S(1):S(2)-1;
>> F = @(d)diag(flipud(a),d);
>> b = cell2mat(arrayfun(F,V(:),'uni',0)).'
b =
     2     7     4     2     9     7    12     5     5    11    41     7    54    45     9    21