step
OPL expression (scheduling) of a cumulative function
Purpose
OPL expression (scheduling) of a cumulative function.
context | type |
---|---|
Model files (.mod) |
cumulFunction |
Syntax
cumulFunction f = step(u, h); Where: int u; int h; cumulFunction f;
Description
Step is an elementary cumulative function expression representing the contribution starting at a point in time. Step covers the production or consumption of a cumulative resource.
The time u is the start of production or consumption and the height of the function is represented by h.
Note that a cumulfunction is constrained to be non-negative if it is involved in a <= or alwaysIn constraint. Also, <= and alwaysIn constraints on cumulfunction expressions cannot be used in meta-constraints.
Example
A set of producing and consuming activities on a tank with a given capacity and safety level.
int SafetyLevel = ...; int Capacity = ...; int StartLevel = ...; int QProd[p in 1..NProd] ...; int QCons[c in 1..NCons] ...; dvar interval AProd[p in 1..NProd] ...; dvar interval ACons[c in 1..NCons] ...; cumulFunction level = step(0, StartLevel) + sum (p in 1..NProd) stepAtEnd(AProd[p], QProd[p]) - sum (c in 1..NCons) stepAtStart(ACons[c], QCons[c]); subject to { alwaysIn(level, 0, maxint, SafetyLevel, Capacity); };