The following code
console.log(Math.pow(2, 53));
console.log(Math.pow(2, 53) + 1);
produces exactly same output for both calculations:
9007199254740992
Why?
-
Possible duplicate: stackoverflow.com/questions/307179/…Ivo Wetzel– Ivo Wetzel2011-01-30 01:03:01 +00:00Commented Jan 30, 2011 at 1:03
Add a comment
|
2 Answers
The result you see occurs because Math.Pow() is working with floating point numbers, and when you reach the 16th decimal digit, you can't necessarily add one to the least significant decimal digit of the value and expect the result to change.
There are typically, in a 64-bit (8-byte) IEEE 754 floating-point binary value, 53 bits for the mantissa (including the implied 1-bit). Your calculation Math.Pow(2, 53) requires 54 bits in the mantissa to be guaranteed of a change. If you add 2, you should see the change.
answered Jan 30, 2011 at 1:01
Jonathan Leffler
759k145 gold badges961 silver badges1.3k bronze badges
