- "use strict";
-
- var log = Math.log;
-
- module.exports = function (value) {
- if (isNaN(value)) return NaN;
- value = Number(value);
- if (value < -1) return NaN;
- if (value > 1) return NaN;
- if (value === -1) return -Infinity;
- if (value === 1) return Infinity;
- if (value === 0) return value;
- return 0.5 * log((1 + value) / (1 - value));
- };
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