'use strict' var bn2num = require('./lib/bn-to-num') var ctz = require('./lib/ctz') module.exports = roundRat // Round a rational to the closest float function roundRat (f) { var a = f[0] var b = f[1] if (a.cmpn(0) === 0) { return 0 } var h = a.abs().divmod(b.abs()) var iv = h.div var x = bn2num(iv) var ir = h.mod var sgn = (a.negative !== b.negative) ? -1 : 1 if (ir.cmpn(0) === 0) { return sgn * x } if (x) { var s = ctz(x) + 4 var y = bn2num(ir.ushln(s).divRound(b)) return sgn * (x + y * Math.pow(2, -s)) } else { var ybits = b.bitLength() - ir.bitLength() + 53 var y = bn2num(ir.ushln(ybits).divRound(b)) if (ybits < 1023) { return sgn * y * Math.pow(2, -ybits) } y *= Math.pow(2, -1023) return sgn * y * Math.pow(2, 1023 - ybits) } }