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| From: | Michael Orlitzky <mjo@g.o> | ||
|---|---|---|---|
| To: | gentoo-user@l.g.o | ||
| Subject: | Re: [gentoo-user] 69.99 != 69.99 | ||
| Date: | Sat, 22 Aug 2015 18:04:29 | ||
| Message-Id: | 55D8B9A1.90407@gentoo.org | ||
| In Reply to: | Re: [gentoo-user] 69.99 != 69.99 by allan gottlieb |
||
| 1 | On 08/22/2015 01:27 PM, allan gottlieb wrote: |
| 2 | >> |
| 3 | >> Floating point addition isn't even commutative: |
| 4 | >> |
| 5 | >> > 0.1 + 0.2 + 0.3 |
| 6 | >> 0.6000000000000001 |
| 7 | >> > 0.1 + (0.2 + 0.3) |
| 8 | >> 0.6 |
| 9 | > |
| 10 | > That demonstrates non-associativity. I believe floating point is |
| 11 | > commutative: a+b = b+a |
| 12 | > |
| 13 | |
| 14 | Derp, thanks, you're right =) |
| 15 | |
| 16 | ...but it's not commutative either: |
| 17 | |
| 18 | >>> nan = float('nan') |
| 19 | >>> nan + 1 == 1 + nan |
| 20 | False |
| 21 | |
| 22 | I'm cheating a bit there, the real problem is: |
| 23 | |
| 24 | >>> nan == nan |
| 25 | False |