model "Transportation"
	
	uses "mmxprs"			!Xpress Optimiser
	
	declarations			!Declare parameters and variables
		SUPPLY= 1..3		!Array for supply points
		DEMAND= 1..4		!Array for demand points
		
		!Supply limit
		s: array(SUPPLY) of integer			
		!Demand amount
		d: array(DEMAND) of integer			
		!Unit transportation cost
		c: array(SUPPLY,DEMAND) of integer	
		
		!Decision variable: number of units shipped from 
		!supply point i to demand point j
		x: array(SUPPLY,DEMAND) of mpvar	
	end-declarations
	
	!Initialise input parameters
	s:= [35,50,40]
	d:= [45,20,30,30]
	c:= [8,6,10,9,
	     9,12,13,7,
	     14,9,16,5]

	!Objective function
	TotalCost:= sum(i in SUPPLY, j in DEMAND) c(i,j)*x(i,j)
	
	!Constraints
	forall(i in SUPPLY) sum(j in DEMAND) x(i,j) = s(i)
	
	forall(j in DEMAND) sum(i in SUPPLY) x(i,j) = d(j)
	
	!Optimisation statement
	minimise(TotalCost)
	
	!Display results
	writeln("Total cost is $", getobjval, ".")
	
	forall(i in SUPPLY, j in DEMAND)
		writeln("x(", i, ",", j, ") = ", getsol(x(i,j)))

end-model