Learning Guide Learning Guide

192 • Chapter 5: Evaluation and Simplification5You can use the eval command to control the level of evaluation of anexpression. If you call eval with just one argument, then eval evaluatesthat argument fully.> eval(x);5A second argument to eval specifies how far you want to evaluate thefirst argument.> eval(x, 1);y> eval(x, 2);z> eval(x, 3);5The main exceptions to the rule of full evaluation are special datastructures like tables, matrices, and procedures, and the behavior of localvariables inside a procedure.Last-Name EvaluationThe data structures array, table, matrix, and proc have a special evaluationbehavior called last-name evaluation.> x := y;x := y> y := z;y := z