Question

I am trying to write all the 6-bit permutations of 0s and 1s using recursion (i.e., [0 0 0 0 0 1], [0 0 0 0 1 0], [0 0 0 0 1 1], [0 0 0 1 0 0], … [1 1 1 1 1 1]). I’m following a tip I got from Yahoo! Answers I’ve got the following but it just doesn’t go all the way to the end and there are duplicate entries.

function [c] = myIEEEBaby_all_decimals(h, n)

% n: number of characters more to add

if n == 0
   converter(h);
   return 
end

in1 = [h 1];
in2 = [h 0];

converter(in1);
converter(in2);

if length(h) < n
    myIEEEBaby_all_decimals([in1], n-1)
    myIEEEBaby_all_decimals([in2], n-1)
end

end

function [d] = converter(IEEE)
% convert custom IEEE representation to decimal

IEEE = [zeros(1,6-length(IEEE)), IEEE];

s = IEEE(1);

characteristic = IEEE([2,3]);
k = find(fliplr(characteristic)) - 1;
c = sum(2.^k);

fraction = IEEE([4:6]);
f = sum(2.^-(find(fliplr(fraction))));

d = (-1)^s*2^(c-1)*(1+f);

disp([num2str(IEEE),' : ', num2str(d)]);

end

The output (MATLAB) is just:

>> myIEEEBaby_all_decimals([],6)
0  0  0  0  0  1 : 0.75
0  0  0  0  0  0 : 0.5
0  0  0  0  1  1 : 0.875
0  0  0  0  1  0 : 0.625
0  0  0  1  1  1 : 0.9375
0  0  0  1  1  0 : 0.6875
0  0  1  1  1  1 : 1.875
0  0  1  1  1  0 : 1.375
0  0  1  1  0  1 : 1.625
0  0  1  1  0  0 : 1.125
0  0  0  1  0  1 : 0.8125
0  0  0  1  0  0 : 0.5625
0  0  1  0  1  1 : 1.75
0  0  1  0  1  0 : 1.25
0  0  1  0  0  1 : 1.5
0  0  1  0  0  0 : 1
0  0  0  0  0  1 : 0.75
0  0  0  0  0  0 : 0.5
0  0  0  0  1  1 : 0.875
0  0  0  0  1  0 : 0.625
0  0  0  1  1  1 : 0.9375
0  0  0  1  1  0 : 0.6875
0  0  0  1  0  1 : 0.8125
0  0  0  1  0  0 : 0.5625
0  0  0  0  0  1 : 0.75
0  0  0  0  0  0 : 0.5
0  0  0  0  1  1 : 0.875
0  0  0  0  1  0 : 0.625
0  0  0  0  0  1 : 0.75
0  0  0  0  0  0 : 0.5

Answer 1

Simply iterate from 0 to 2⁶-1 and call Matlab’s dec2bin(...) function. You could pad the result with zero’s using sprintf(...).