log_n_buggy

#include <iostream>
#include <cmath>

double log_n(double n) { // Big O(log n) Logarithmic  // recursive
    if (n != 0) {
        n = floor(n / 2);
        log_n(n);
    }
    return n;
}

int main() {

std::cout << log_n(8.0) << '\n';

return 0;
}

// returns 4 instead of 3. I thought it was because I used int first but the bug is still here.
// for 7.0 it returns 3 instead. what am I doing wrong?