Forum Discussion
mpvar variables and identifiers
Hi, Is it possible to sum a mpvar and an integer variable into an index of another mpvar ? Example: declarations
x: array(1..10,1..5) of mpvar
y: mpvar
end-declarations
y is_integer
y <= 2
fo...
I would suggest to work with additional variables representing the actual values per task that are selected via the 'Start' (-> 'ifstart') and 'Finish' (-> 'iffinish') variables - assuming that one of these is meant to be non-zero per task, being defined as binaries or SOS-1:
declarations
ifstart: array(1..nTask, 1..nTime) of mpvar ! Start time selectors ('Start')
iffinish: array(1..nTask, 1..nTime) of mpvar ! Completion time selectors ('Finish')
tstart: array(1..nTask) of mpvar ! Start time value per (aggregation of 'ifstart' per task)
tfinish: array(1..nTask) of mpvar ! Completion time (aggregation of 'iffinish' per task)
wait: array(1..nTask) of mpvar ! Variable time in between start and finish
end-declarations
forall(i in 1..nTask) do
! ... define ifstart and iffinish as binary or as one SOS-1 per task ...
sum(j in 1..nTime) ifstart(i,j) = 1
sum(j in 1..nTime) j*ifstart(i,j) = tstart(i)
sum(j in 1..nTime) iffinish(i,j) = 1
sum(j in 1..nTime) j*iffinish(i,j) = tfinish(i)
tstart(i) = tfinish(i)+wait(i) ! The actual relation to be stated
end-do
Note that I have changed the name of the array from 'time' to 'wait' in order to avoid any clashes with the type 'time' that is defined by the Mosel module 'mmsystem'.