An Amsterdam Node Meetup presentation by Luca Maraschi on December 16th 2014: NaN is a Number and (0.1 + 0.2 === 0.3) is not true!JS, and so node.js, are infamous for their number’s management, but are we all right about this? Do we know where this come from? Is it fixable? Can we? An historical odyssey (excursus) from the origin of floating point calculation till modern languages, which will take us analysing the real business value of IEEE754 and floating point precision, with real case scenarios and their resolution in production.

1. Numbers
the
Magic

2. @lucamaraschi

3. Once upon the time…

4. Numbers are not perfect

5. in JS
“primitive value corresponding to a double-precision 64-bit binary format IEEE 754 value”

6. 64bit
s

7. Sign
Sign
Exponent
Mantissa
+
+

8. Sign
exponent
11bit
s

9. Sign
exponent
position of the floating point!

10. Sign
mantissa
52bit
s
1
hidden
bit
+

11. so 0.1 is not really 0.1

12. Fractions
build of the inverse power of 2
only 52 bits of mantissa
and
fix size of 64bits
and

13. 53 bits of exponent
can only represent every second integer

14. Future

15. DEC64
Coefficient
* 10^Exponent
=
by Douglas Crockford

16. DEC64
Coefficient Exponent
8 bits56 bits

17. Physicians accept the
uncertainty of the
measurement
Walter Lewin

18. we are hiring.
icemobile.com/jobs

19. icemobile.com/blog /company/icemobile

20. IceMobileAmsterdam @icemobile@icemobile

21. Adding emotion to transactional loyalty