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Talk:Hamming numbers: Difference between revisions
→Off-by-one error?
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Since hamming(1692) = 2^31, the last one before 2^31 is hamming(1691). I changed it in the problem description. --[[User:Dsnouck|Dsnouck]] 08:56, 3 December 2009 (UTC)
: Originally I had the 1691. Tcl had 1690 so I stored all values in an array and found that 1690 was correct. Since I have checked twice, I have reverted your edit, but please check again (as I will tonight). --[[User:Paddy3118|Paddy3118]] 09:09, 3 December 2009 (UTC)
:: I still believe my original remark was correct. I am not going to re-revert. I changed my Scheme program to show some extra output. Maybe some people that submitted other implementations can also check this. We actually do agree on the value of
::: FWIW, calculating with the Tcl impl...<pre>
:::hamming{1690} = 2123366400
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:::hamming{1693} = 2149908480
:::</pre>My only concern is whether I had an off-by-one error from counting indices from zero or one (i.e., is it ''H''<sub>0</sub> or ''H''<sub>1</sub> that is 1? My impl assumes it is ''H''<sub>1</sub>...) –[[User:Dkf|Donal Fellows]] 10:20, 3 December 2009 (UTC)
:::: So I think it is safe to say that we agree on the value of the 1690th Hamming number. Here it doesn't matter wheter indexing is zero-based or one-based. If we agree that the first Hamming number is 1, it is clear what we mean by the 1690th Hamming number. The only difference between zero-based indexing compared to one-based is that the first Hamming number is called hamming(0) in the former case and hamming(1) in the latter. Similarly for the 1690th Hamming number: with zero-based indexing it is called hamming(1689) as compared to hamming(1690) with one-based indexing. Anyway, to me it still looks like the last Hamming number before 2^31 is the 1691th, since the 1692th Hamming number is equal to 2^31. --[[User:Dsnouck|Dsnouck]] 10:48, 3 December 2009 (UTC)
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