Talk:Arithmetic coding/As a generalized change of radix: Difference between revisions

no edit summary
No edit summary
No edit summary
Line 62:
::::::::::::: But, also: '''"The cumulative frequency is the total of all frequencies below it in a frequency distribution (a running total of frequencies)"''' on the wikipedia page conflicts with a cumulative frequency encoding of letters and 1150764267498783364 as the encoding for 'TOBEORNOTTOBEORTOBEORNOT'. (To get 1150764267498783364, I needed cumulative frequencies in alphabetic order rather than in frequency order.)
:::::::::::::That said, I am not maintaining that the wikipedia page is incorrect - merely that it conflicts with some parts of a number of the implementations of this task. (Well, that, and mostly useless. But I don't see much use for any implementation of this technique, so I'm ignoring that issue.) --[[User:Rdm|Rdm]] ([[User talk:Rdm|talk]]) 23:53, 31 January 2016 (UTC)
:::::::::::::: "involved symbols form an ordered set and each symbol in the ordered set denotes a sequential integer" means that the symbols come from some set with an ordering. In this case, they are using the set of letters and using ascending alphabetic order (and in the Rosetta Code implementation we are using the set of all bytes and using ascending character byte value order). All that matters is that A < B < C < D < ... The actual *values* are COMPLETELY IRRELEVANT to the algorithm -- they are just used in the encoding and decoding dictionaries. The reason that they are requiring that there is an ordering of the symbols is because "cumulative" requires some order of accumulation; that's the only reason why these "sequential integers" is even mentioned. Your confusion comes from the fact that you are wrongfully thinking that these "sequential integers" are somehow used in the algorithm. But nowhere in the Wikipedia description does it say anything to that effect. You are completely imagining that, possibly because the cumulative frequency in this example is coincidentally similar to the integer values they assign. The Wikipedia description shows very clearly where the cumulative frequencies come from and the "sequential integers" never factor into any of that. --[[User:Spoon!|Spoon!]] ([[User talk:Spoon!|talk]]) 04:14, 1 February 2016 (UTC)
 
== Goof? (part 2) ==
Anonymous user