Faster way for decimal to binary conversion

Question

Considering an array of integer numbers:

X = [1, 3, 3, 3,2,3 ,1,1,2,3]

I want to convert each number to its 4 bit binary equivalent. I have done the following, but the result is not correct. It seems that the MSB and LSB are reversed. I tried using MATLAB's function with decimal_to_bin =dec2bin(X) but even this output is wrong.

How can I fix this?

X = [1, 3, 3, 3,2,3 ,1,1,2,3];
b = 4;
lookup_table = generate_lookupTable(b);
BinaryX = lookup_table(X,:);



function result = generate_lookupTable(b)

% generate binary code

k = 2^b;
result = zeros(k,b);

for i=1:k
    for j=1:b
        result(i,j) = bitand(uint8(2^(j-1)),uint8(i-1))/uint8(2^(j-1));
    end
end

end

The output that I got is BinaryX

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

Answer 1

I think beaker means something along these lines:

% Your vector
X = [1, 3, 3, 3,2,3 ,1,1,2,3];

% number of bits to use 
numbits = 4;

% Create lookup table
little_endian = true;

LUT = dec2bin(0:15, numbits) == '1';
if ~little_endian
    LUT = fliplr(LUT); end

% The conversion 
bits = LUT(X(:) + 1, :)

Alternatively, you can do what dec2bin does, but without all the fuss around it:

bits = (rem(floor(X(:)*pow2(1-numbits:0)),2) == 1);