In mathematics and set theory, a tuple is an ordered set of items where the type
of the item in a particular place is fixed. For example, you could have a tuple
of numbers, in which case it would be a vector. You could have a tuple of (name,
age, phonenumber), in which case it looks like a struct in C. The locations of
the items in the tuple can be represented by integers (1 to length, or 0 to
length-1, depending on how you like to count). Since this defines a map from the
set {1..length} to the corresponding values, you can define an identity
relationship between the set {1..length} and another equaly sized set of names,
or keys. This has the knock-on effecth that you can retrieve values by name,
making a tuple look very much like a hash table. This is how Perl models
objects, or JavaBeans model properties (with the indexes being replaced with
unique property names).
In programming, tuples are normaly represented as lists or arrays. When the type
of each element can be different, then structs or simple objects are used.
Sparse tuples (where most values are empty or zero) can efficiently be
represented by a hash table or map. In a database, each table defines a type of
tuple, and the SQL join operations boil down to cross and dot products of these
tuples.
Hope that helps.
Matthew
armel wrote:
> Hello,
> Tuple, what does it mean exactly, I understand it used to represent tuples
> by the javax.vecmath package.
> But wich is the origin of this word in programmation ? Perhaps it help me to
> understand.
>
> Thanks
> Armel
> ---
> '' � cette heure, des enfants naissent en Bretagne.
> Seront-ils bretons ? Nul ne le sait.
> � chacun, l'�ge venu, la d�couverte ou l'ignorance.'' Lebesque Morvan
>
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