function i = binsearch_r(array, val, low, high)
  if ( high < low )
    i = 0;
  else
    mid = floor((low + high) / 2);
    if ( array(mid) > val )
      i = binsearch_r(array, val, low, mid-1);
    elseif ( array(mid) < val )
      i = binsearch_r(array, val, mid+1, high);
    else
      i = mid;
    endif
  endif
endfunction