Javascript错误地更改了简单乘法的结果。我怎么才能修复它？

Question

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function roundUp(num, precision) {
  return Math.ceil(num * precision) / precision;
}

var num = 0.07;
var precision = 100;
console.log(roundUp(num, precision));

​

当函数的参数是7.000000000001和100时，"num * precision“乘法会得到类似于”0.07“的结果，而ceil函数会将其向上舍入为8。

我该如何解决这个问题呢？我有big.js，但是做不出来。

Answer 1

另一个天真的尝试，因为这里的函数是天花板。这试图使误差因子将数字降低ε倍，以使我们得到6.9999999。而不是7.00000000..1

又是一次天真的尝试！

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function roundUp(num, precision) {
      return Math.ceil((num * precision) - (num * precision * Number.EPSILON)) / precision;
}

console.log(roundUp(0.07, 100))
console.log(roundUp(0.03, 100))
console.log(roundUp(0.002, 1000))
console.log(roundUp(0.00222, 1000))
console.log(roundUp(0.006, 1000))
console.log(roundUp(0.00600000000000000000001, 10000000000000000000));//broken
console.log(roundUp(0.006001, 10000000));
console.log(roundUp(0.0333, 1000))
console.log(roundUp(0.07777777, 10))
console.log(roundUp(0.07777777, 100))
console.log(roundUp(0.07777777, 1000))
console.log(roundUp(0.07777777, 10000))
console.log(roundUp(0.07777777, 100000))
console.log(roundUp(0.07777777, 1000000))

console.log(roundUp(0.33333333333333, 1000000))

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