topic Re: proc optmodel: no of decimals in arrray in Mathematical Optimization, Discrete-Event Simulation, and OR

proc optmodel: no of decimals in arrray

Phoenix_LJ — Mon, 13 Sep 2021 13:39:12 GMT

proc optmodel;
	/*declare	*/
	set rows = 1..10;
	set cols = 1..6;
	var X{rows,cols} >=0 <=50;
	max z=sum(x[6,1],x[6,2],x[6,3]);


	/*constrains	*/
	con varcon1{i in 1..6}: 0<=X[1,i]<=10;
	con varcon2{i in 1..6}: 0<=X[1,i]<=25;
	con varcon3{i in 1..6}: 0<=X[1,i]<=15;
	con varcon4{i in 1..6}: 0<=X[1,i]<=23;
	con varcon5{i in 1..6}: 0<=X[1,i]<=10;
	con varcon6{i in 1..6}: 0<=X[1,i]<=20;
	con varcon7{i in 1..6}: 0<=X[1,i]<=20;
	con varcon8{i in 1..6}: 0<=X[1,i]<=20;
	con varcon9{i in 1..6}: 0<=X[1,i]<=5;
	con varcon10{i in 1..6}: 0<=X[1,i]<=2;

	/*constrains	*/
	con colcon1{i in 1..10}:  0<=x[i,1]<=50;
	con colcon2{i in 1..10}:  0<=x[i,2]<=35;
	con colcon3{i in 1..10}:  0<=x[i,3]<=15;
	con colcon4{i in 1..10}:  0<=x[i,4]<=8;
	con colcon5{i in 1..10}:  0<=x[i,5]<=12;
	con colcon6{i in 1..10}:  0<=x[i,6]<=30;

	/*constrains	*/
	con equal1:	sum{i in 1..6}(x[1,i]) = 10;
	con equal2:	sum{i in 1..6}(x[2,i]) = 25;
	con equal3: sum{i in 1..6}(x[3,i]) = 15;
	con equal4:	sum{i in 1..6}(x[4,i]) = 10;
	con equal5:	sum{i in 1..6}(x[5,i]) = 20;
	con equal6:	sum{i in 1..6}(x[6,i]) = 20;
	con equal7:	sum{i in 1..6}(x[7,i]) = 20;
	con equal8:	sum{i in 1..6}(x[8,i]) = 5;
	con equal9:	sum{i in 1..6}(x[9,i]) = 2;
	con equal10:sum{i in 1..6}(x[10,i]) = 23;

	SOLVE;
	print x;
QUIT;

Please run this code,

the question is

How do I keep array X two decimal places

Re: proc optmodel

Ksharp — Mon, 13 Sep 2021 12:12:40 GMT

Better post it at OR forum. And calling @RobPratt

Re: proc optmodel: no of decimals in arrray

RobPratt — Mon, 13 Sep 2021 16:31:55 GMT

The SUM() function triggers the NLP solver to be used. If you change the objective declaration as follows, the LP solver will instead be used, and the (totally unimodular) structure of your problem naturally yields an integer solution:

/*	max z=sum(x[6,1],x[6,2],x[6,3]);*/
	max z = x[6,1] + x[6,2] + x[6,3];

X
	1	2	3	4	5	6
1	2	2	2	2	2	0
2	25	0	0	0	0	0
3	15	0	0	0	0	0
4	10	0	0	0	0	0
5	20	0	0	0	0	0
6	20	0	0	0	0	0
7	20	0	0	0	0	0
8	5	0	0	0	0	0
9	2	0	0	0	0	0
10	23	0	0	0	0	0

Re: proc optmodel: no of decimals in arrray

RobPratt — Mon, 13 Sep 2021 17:53:59 GMT

Also notice that your varcon10 constraint makes the other nine varcon* constraints redundant. Are you sure that this model correctly captures the problem you want to solve?

X
	1	2	3	4	5	6
1	2	2	2	2	2	0
2	25	0	0	0	0	0
3	15	0	0	0	0	0
4	10	0	0	0	0	0
5	20	0	0	0	0	0
6	20	0	0	0	0	0
7	20	0	0	0	0	0
8	5	0	0	0	0	0
9	2	0	0	0	0	0
10	23	0	0	0	0	0

X
	1	2	3	4	5	6
1	2	2	2	2	2	0
2	25	0	0	0	0	0
3	15	0	0	0	0	0
4	10	0	0	0	0	0
5	20	0	0	0	0	0
6	20	0	0	0	0	0
7	20	0	0	0	0	0
8	5	0	0	0	0	0
9	2	0	0	0	0	0
10	23	0	0	0	0	0

X
	1	2	3	4	5	6
1	2	2	2	2	2	0
2	25	0	0	0	0	0
3	15	0	0	0	0	0
4	10	0	0	0	0	0
5	20	0	0	0	0	0
6	20	0	0	0	0	0
7	20	0	0	0	0	0
8	5	0	0	0	0	0
9	2	0	0	0	0	0
10	23	0	0	0	0	0