/**
 * returns the largest positive number in a given array
 * @param  {Array} arr     [the array to act on]
 * @return {Array}         [the largest number]
 */
function getLargestPosNumInArr(arr) {
  return arr.reduce(function(prevVal, curVal) {
    if (curVal > prevVal) {
      prevVal = curVal;
    }
    return prevVal;
  }, 0);
}