hammingweight

This question already has answers here : Calculating Hamming weight efficiently in matlab (9 answers) Closed 6 years ago . Quite a simple problem: I have a list of integers, e.g., a = [7 8] Now I want to have a seperate list, that contains the Hamming Weight (that is the number of 1 bits in the binary represenation) for each of the integers in the list. That means the result for the integer list above should look as follows: res = [3 1] Anyone an idea how I could do this quickly? This is a little hacky, but it works: res = sum( dec2bin(a).' == '1' ); It converts a to binary representation,

Given a certain integer x , I wish to compute the next higher integer y which has a certain hamming weight w . Mind that the hamming weight of x does not have to be w as well. So, for example x = 10 (1010) and w = 4 the result should be y = 15 (1111). Obviously, I could achieve this by just incrementing x but that would be a very slow solution for high numbers. Can I achieve this by the means of bit shifts somehow? There are three cases: the Hamming weight (a.k.a. bitwise population count) is reduced, unchanged, or increased. Increased Hamming weight Set enough successive low-order 0-bits to

I need C code to return the number of 1's in an unsigned char in C. I need an explanation as to why it works if it's not obvious. I've found a lot of code for a 32-bit number but not much for an unsigned char. The same code will work for an unsigned char. Loop over all bits testing them. See this . const unsigned char oneBits[] = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4}; unsigned char CountOnes(unsigned char x) { unsigned char results; results = oneBits[x&0x0f]; results += oneBits[x>>4]; return results } Have an array that knows the number of bits for 0 through 15. Add the results for each nibble.

I'm looking for a fast way to calculate the hamming weight/population count/"the number of 1 bits" of a BINARY(1024) field. MySQL has a BIT_COUNT function that does something like that. I couldn't find a similar function in T-SQL? Or would you suggest storing the binary data in a field of another type? If you don't know what I'm talking about, here's a Wikipedia article about the hamming weight . You could use a helper table with precalculated Hamming weights for small numbers, like bytes, then split the value accordingly, join to the helper table and get the sum of partial Hamming weights as

Given a MATLAB uint32 to be interpreted as a bit string, what is an efficient and concise way of counting how many nonzero bits are in the string? I have a working, naive approach which loops over the bits, but that's too slow for my needs. (A C++ implementation using std::bitset count() runs almost instantly). I've found a pretty nice page listing various bit counting techniques, but I'm hoping there is an easy MATLAB-esque way. http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetNaive Update #1 Just implemented the Brian Kernighan algorithm as follows: w = 0; while ( bits > 0 )

Assume we have a integer of bitsize n=4; The problem I am describing is how you would go about indexing a number to an array position based on the Hamming weight and its value knowing the bitsize . E.g. An array with 16 elements for bitsize 4 would/could look like this: |0|1|2|4|8|3|5|6|9|10|12|7|11|13|14|15| Where elements are grouped by their Hamming weight(necessary) and sorted based on size(not necessary). Sorting is not necessary as long as you can take e.g. 3(0011) do some operations and get back index 5, 5(0101) -> 6 etc. All combinations of n bits will be present and there will be no