This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
 Assignments Mathematica's symbolic architecture supports a highly generalized notion of assignment, in which you can specify a transformation for any class of expressions defined by a Mathematica pattern. Simple cases correspond to assignments for "variables", "indexed variables" or "structure elements". Other cases define functions or general transformations. x=v — assign a value (Set) {x,y}={u,v} — assign multiple values {x,y}={y,x} — swap values      a[[i]]=v — assign a value to a list/array/expression element      x++ (Increment)  ▪ ++x (PreIncrement)  ▪ x+=y (AddTo) x-- (Decrement)  ▪ --x (PreDecrement)  ▪ x-=y (SubtractFrom) x*=y (TimesBy)  ▪ x/=y (DivideBy) AppendTo, PrependTo — add elements to a list      Function Definitions f[x_]:=body — define a function      Forms of Assignment lhs=rhs — immediate assignment, with rhs evaluated at the time of assignment lhs:=rhs — delayed assignment, with rhs re-evaluated every time it is used      f/:lhs=rhs, f/:lhs:=rhs — associate assignments with the head f lhs^=rhs, lhs^:=rhs — define "upvalues" associated with the leading head in lhs      Clearing Assignments x=. — unset the value of x (Unset) Clear — clear all values associated with a symbol      Information about Assignments ?x (Information) — get information about all assignments for x TUTORIALS Associating Definitions with Different Symbols Making Definitions Defining Variables Defining Numerical Values Defining Functions Making Definitions for Functions Immediate and Delayed Definitions MORE ABOUT Variables and Functions