Continuous variables

All through this chapter we have worked with the decision variable type cpvar (discrete variables). A second variable type in Xpress Kalis are continuous variables (type cpfloatvar). Such variables are used in a similar way to what we have seen above for discrete variables, for example:

 setparam("KALIS_DEFAULT_CONTINUOUS_LB", 0)
 setparam("KALIS_DEFAULT_CONTINUOUS_UB", 10)

 declarations
  x,y: cpfloatvar
 end-declarations

 x >= y                   ! Define a constraint
                          ! Retrieve information about continuous variables
 writeln(getname(x), ":", getsol(x))
 writeln(getlb(y), " ", getub(y)) 

A few differences in the use of the two decision variable types exist:

• Constraints involving cpfloatvar cannot be strict inequalities (that is, only the operators <=, >=, and = may be used).
• Most global constraints (see Chapter Constraints) only apply to cpvar; also applicable to cpfloatvar are maximum and minimum relations.
• Search strategies enumerating the values in a variable's domain can only be used with cpvar; with cpfloatvar domain splitting must be used (see Chapter Enumeration).
• Access functions for enumerating domain values such getnext are not applicable to cpfloatvar.