Get the integer position of the set bit in a bit vector (field)

find_set_bit_position.m

// Example:
// 000100 (the value of bit vector x) returns 16 (use (x << 4) & 1UL to verify)
//          To find the position of the set bit that returned 16,
//           use floor(log2(16)) to get 4.

// Creates bit vector j and sets the ith bit out of 5…
// …returns the value of bit vector j, which is i raised to the power of two (2, 4, 8, 16, 32)…
// …returns the position of the set bit in bit vector j, which should coincide with i
//
for (int i = 1; i < 5; i++) {
	unsigned int j = (1UL << i);
	int position = floor(log2(j));
	printf("position of j (%d) == %d\t(%d)\n", j, position, i);
}

// Other solutions use a recursive function (or block) to iterate each bit in the vector,
// counting the number of 0s before returning the sum at the first set bit:
//
long (^Log2n_recursive)(unsigned int) = ^ long (unsigned int property) {
	return (property > 1) ? 1 + Log2n_recursive(property / 2) : 0;
//     return floor(log2(property)); // replace the line above with this more efficient, unconditional, non-recursive and nonbranching algorithm
};