how to reverse a matrix from bottom to top row wise and then pick out odd rows?

hello

if i have this matrix A =

        10000
        00010
        10101
        10011
        10000
        00001
the rows can be from 1 to 2.^m-2 where m lets say 5. so that gives us 30 rows. i want to flip these rows from bottom to top so that the last row is the first, the second last becomes the second, the third last the third.

flipped A =

      00001
      10000
      10011
      10101
      00010
      10000

then i want to pick the odd numbered rows from the flipped order (the first, third, fifth) such that 1:2:2t rows are picked out and displayed as shown below (here t = 3)

         00001
         10011
         00010

can anyone help out with this?

regards

[Jan]

What doe "matrix A = 10000 ..." exactly mean? Is this a CHAR matrix /then you forgot the quotes), or a double matrix (then the leading zeros are meaningless). It is not clear, what "the rows can be from 1 to 2.^m-2" means. Do you mean the size of the matrix or the decimal representatioon of the values of the elements or rows?

Answer 1

[Andrei Bobrov]

A =[10000
        00010
        10101
        10011
        10000
        00001];

A = num2str(A);
b = strrep(A(:)',' ','0');
A(:) = b; % A is string

out1 = flipud(A);
out2 = out1(1:2:end,:);

ADD after the Malik's comment

A = [ 1  1  0  0  0  0
        1  0  1  0  0  1
        1  0  1  0  0  1
        1  0  1  1  1  1
        1  0  1  0  0  1
        1  1  1  0  1  1
        1  0  1  1  1  1
        1  1  1  1  0  1
        1  0  1  0  0  1
        1  1  1  0  1  1
        1  1  1  0  1  1
        1  1  0  1  1  1
        1  0  1  1  1  1
        1  1  0  1  1  1
        1  1  1  1  0  1
        1  0  0  1  0  1
        1  0  1  0  0  1
        1  0  1  1  1  1
        1  1  1  0  1  1
        1  1  1  1  0  1
        1  1  1  0  1  1
        1  1  0  1  1  1
        1  1  0  1  1  1
        1  0  0  1  0  1
        1  0  1  1  1  1
        1  1  1  1  0  1
        1  1  0  1  1  1
        1  0  0  1  0  1
        1  1  1  1  0  1
        1  0  0  1  0  1
        1  0  0  1  0  1];

out1 = flipud(A);
out2 = out1(1:2:end,:);

[Malik]

this does not work with a big matrix as below:

        1  1  0  0  0  0
        1  0  1  0  0  1
        1  0  1  0  0  1
        1  0  1  1  1  1
        1  0  1  0  0  1
        1  1  1  0  1  1
        1  0  1  1  1  1
        1  1  1  1  0  1
        1  0  1  0  0  1
        1  1  1  0  1  1
        1  1  1  0  1  1
        1  1  0  1  1  1
        1  0  1  1  1  1
        1  1  0  1  1  1
        1  1  1  1  0  1
        1  0  0  1  0  1
        1  0  1  0  0  1
        1  0  1  1  1  1
        1  1  1  0  1  1
        1  1  1  1  0  1
        1  1  1  0  1  1
        1  1  0  1  1  1
        1  1  0  1  1  1
        1  0  0  1  0  1
        1  0  1  1  1  1
        1  1  1  1  0  1
        1  1  0  1  1  1
        1  0  0  1  0  1
        1  1  1  1  0  1
        1  0  0  1  0  1
        1  0  0  1  0  1

[Malik]

the out2 is: 1000000001000001 1001001001000001 1001000001001001 1000001001001001 1001000001001001 1001001000001001 1001001000001001 1000001000000001 1001001001000001 1000001001001001 1001001000001001 1000001000000001 1000001001001001 1000001000000001 1000001000000001 1001000000000000 (in a single column) and the length of each row has changed dont know why

[Andrei Bobrov]

see ADD part in my answer.

[Malik]

yes it works! Thanks!

[Malik]

i have another question and since it is linked to this i find it convenient to post it right here, if i need to take the lcm of the binary rows that have come ut finally in out2 i am doing this:

converting each row to dec using num2str(bin2dec(out2(:))) (but doesnt work )

then applying lcm (out3)

% but the lcm function wont work for more than two numbers which is pretty challenging here, how to work through this?

[Malik]

i have converted out3 = num2str(out2(:)) to string this way.

Now to convert out3 to decimal i need to pick the string 5 at a time and convert to dec: bin2dec(out3(1:end)) then take the lcm of all the integers.