40 var pow = function (x, n, acc) {  argument
41   return n === 0 ? acc : n % 2 === 1 ? pow(x, n - 1, acc * x) : pow(x * x, n / 2, acc);
43 var log = function (x) {  argument
45   var x2 = x;
66     var x = aNumberValue(this, ERROR);  variable
73     if (x != x) return 'NaN';
74     if (x <= -1e21 || x >= 1e21) return String(x);
75     if (x < 0) {
77       x = -x;
79     if (x > 1e-21) {
80       e = log(x * pow(2, 69, 1)) - 69;
81       z = e < 0 ? x * pow(2, -e, 1) : x / pow(2, e, 1);