CODEWITHSUNDEEP
javascriptnumbers
Cibo FATA8
Cibo FATA8

Reputation: 101

JavaScript Epsilon when multiplying

I was thinking that equality in ES6 is closed case, like this basic example:

x = 0.2;
y = 0.3;
z = 0.1;
equal = (Math.abs(x - (y - z)) < Number.EPSILON); // true
console.log(equal)

But it does not work in this(multiplying) case:

x = 2.3;
y = 23;
z = 0.1;
equal = (Math.abs(x - (y * z))) < Number.EPSILON; // false
console.log(equal)

Am I thinking wrong? Is it only designed for plus and minus operations? How can I safely fix it (it is true when you multiple epsilon by anything bigger than 2)?

Upvotes: 1

Views: 362

Answers (1)

Ashish Ranjan
Ashish Ranjan

Reputation: 5543

Try printing the value of Math.abs(x - (y * z)) and EPSILON :

x = 2.3;
y = 23;
z = 0.1;
equal = (Math.abs(x - (y * z))) < Number.EPSILON; // false
console.log(equal)
console.log(Math.abs(x - (y * z)))
console.log(Number.EPSILON)
console.log(Math.abs(x - (y * z)) == 2*Number.EPSILON)

To avoid this you should be checking the order of the difference , and compare it to EPSILON, instead of the comparing the actual value :

x = 2.3;
y = 23;
z = 0.1;
equal = (Math.abs(x - (y * z)))/ Number.EPSILON < 10;

console.log(equal)

Upvotes: 1

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