JavaScript number approximation

Question

I used function :

fixedTo(1)

to approximate a number like this:

-3.43321e-11

but the problem is that the result of approximation is:

-0.0

with minus sign.

This is a problem because in math doesn't exist 0 with minus sign and if I do:

if(-0.0 === 0.0){}

it returns me false insted of true. How can I resolve it?

please post your entire code, i mean the approximation method — Akshay Arora
– Akshay Arora, Commented Feb 2, 2015 at 15:15
The problem is that comparison is inside an iteraction and I need sign of number except for zero @FrédéricHamidi — Stefano Maglione
– Stefano Maglione, Commented Feb 2, 2015 at 15:15
If you Google JavaScript negative zero you'll find lots of posts. — Travis Pettry
– Travis Pettry, Commented Feb 2, 2015 at 15:15

Lars Ebert-Harlaar · Accepted Answer · 2015-02-02 15:15:42Z

3

That is a common problem when comparing float values. Float values are almost never exactly like you write them. So your -0.0 is in reality more like -0.000001 or something.

If you want to compare float values, you have to deal with a certain amount of error, like this:

if(Math.abs(value1 - value2) < 0.001) {

So you basically treat all floats whose difference is smaller than 0.001 as equal.

answered Feb 2, 2015 at 15:15

Lars Ebert-Harlaar

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