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?

possible duplicate of [Are +0 and -0 the same?](http://stackoverflow.com/questions/7223359/are-0-and-0-the-same) — Travis Pettry, Feb 02 '15 at 15:15
please post your entire code, i mean the approximation method — Akshay Arora, Feb 02 '15 at 15:15
The problem is that comparison is inside an iteraction and I need sign of number except for zero @FrédéricHamidi — Stefano Maglione, Feb 02 '15 at 15:15
If you Google JavaScript negative zero you'll find lots of posts. — Travis Pettry, Feb 02 '15 at 15:15

score 3 · Accepted Answer · answered Feb 02 '15 at 15:15

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.

JavaScript number approximation

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