Maple 9 Learning Guide - Maplesoft

206 • Chapter 6: Evaluation and Simplificationrecently assigned directly to that variable.> test:=proc()> local x, y, z;> x := y;> y := z;> z := 5;> x;> end proc:> test();yCompare this evaluation with the similar interactive example in thissection on page 202. Full evaluation within a procedure is rarely necessaryand can lead to inefficiency. If you require full evaluation within aprocedure, use eval.Commands with Special Evaluation RulesThe assigned and evaln Commands The functions assigned andevaln evaluate their arguments only to the level at which they becomenames.> x := y;x := y> y := z;y := z> evaln(x);xThe assigned command checks if a name has a value assigned to it.> assigned( x );true