ILOG OPL Development Studio Language Reference Manual

Expressions on interval variablesInteger and numerical expressions are available to access or evaluate different attributes ofan interval variable.These expressions can be used, for example, to define a term for the cost function or to connectinterval variables to integer and floating point expressions.The integer expressions are startOf, endOf, lengthOf, and sizeOf and they provide access tothe different attributes of an interval variable. Special care must be taken for optional intervals,as an integer value dval must be specified which represents the value of the expression whenthe interval is absent. If this value is omitted, it is supposed to be 0. For the syntax of integerexpressions, see endOf, lengthOf, sizeOf, and startOf in the OPL Language Quick Reference.The numerical expressions are startEval, endEval, lengthEval, and sizeEval, and they allowevaluation of a piecewise linear function on a given bound of an interval. As with integerexpressions, in the case of optional intervals an integer value dval must be specified whichrepresents the value of the expression when the interval is absent. If this value is omitted, itis supposed to be 0. For the syntax and examples of the use of a numerical expression, seeendEval, lengthEval, sizeEval, and startEval in the OPL Language Quick Reference.Let denote a fixed interval variable. The semantics of these expressions is shown in thetable.156I L O G O P L D E V E L O P M E N T S T U D I O L A N G U A G ER E F E R E N C E M A N U A L