alpha Inertia=
	1
	~	dmnl
	~		|

d Demand=
	"d t-1 Prior Demand" - (1-alpha Inertia)*"epsilon t-1 Prior Disturbance"
	+epsilon Demand Disturbance
	~	widgets/Period
	~		|

"d t-1 Prior Demand"= INTEG (
	(d Demand-"d t-1 Prior Demand")/One Period,
		mu Initial Forecast)
	~	widgets/Period
	~		|

"E[epsilon] Mean Disturbance"=
	0
	~	widgets/Period
	~		|

epsilon Demand Disturbance=
	"E[epsilon] Mean Disturbance"
	+"Var[epsilon] SD Disturbance"*RANDOM NORMAL(-6,6,0,1,seed)
	~	widgets/Period
	~		|

"epsilon t-1 Prior Disturbance"= INTEG (
	(epsilon Demand Disturbance-"epsilon t-1 Prior Disturbance")/One Period,
		0)
	~	widgets/Period
	~		|

F t Prior Forecast= INTEG (
	("F t+1 Demand Forecast"-F t Prior Forecast)/One Period,
		mu Initial Forecast)
	~	widgets/Period
	~		|

"F t+1 Demand Forecast"=
	alpha Inertia*d Demand + (1-alpha Inertia)*F t Prior Forecast
	~	widgets/Period
	~		|

L lead time=
	4
	~	Period
	~		|

mu Initial Forecast=
	1
	~	widgets/Period
	~		|

One Period=
	1
	~	Period
	~		|

q Ordering=
	d Demand + L lead time*("F t+1 Demand Forecast"-F t Prior Forecast)/One Period
	~	widgets/Period
	~		|

"q t-L Receiving"= DELAY MATERIAL (
	q Ordering, L lead time, mu Initial Forecast, 0)
	~	widgets/Period
	~		|

seed=
	6079
	~	dmnl
	~		|

Supply Line= INTEG (
	q Ordering-"q t-L Receiving",
		0)
	~	widgets
	~		~	:SUPPLEMENTARY 
	|

"Var[epsilon] SD Disturbance"=
	1
	~	widgets/Period
	~		|

x Inventory= INTEG (
	+"q t-L Receiving"-d Demand,
		x0 Initial Inventory)
	~	widgets
	~		~	:SUPPLEMENTARY 
	|

x0 Initial Inventory=
	0
	~	widgets
	~		|

********************************************************
	.Control
********************************************************~
		Simulation Control Parameters
	|

FINAL TIME  = 1000
	~	Period
	~	The final time for the simulation.
	|

INITIAL TIME  = 1
	~	Period
	~	The initial time for the simulation.
	|

SAVEPER  = 
        TIME STEP
	~	Period
	~	The frequency with which output is stored.
	|

TIME STEP  = 1
	~	Period
	~	The time step for the simulation.
	|

\\\---/// Sketch information - do not modify anything except names
V300  Do not put anything below this section - it will be ignored
*View 1
$192-192-192,0,Times New Roman|12||0-0-0|0-0-0|0-0-0|-1--1--1|-1--1--1|96,96
10,1,epsilon Demand Disturbance,352,540,89,11,0,3,0,0,0,0,0,0
10,2,"d t-1 Prior Demand",368,318,40,20,3,3,0,0,0,0,0,0
10,3,"epsilon t-1 Prior Disturbance",422,634,40,20,3,3,0,0,0,0,0,0
1,4,1,22,1,0,0,0,0,64,0,-1--1--1,,1|(428,494)|
1,5,3,22,1,0,0,0,0,64,0,-1--1--1,,1|(468,533)|
1,6,2,21,1,0,0,0,0,64,0,-1--1--1,,1|(458,354)|
12,7,48,262,634,8,8,0,3,0,0,-1,0,0,0
11,8,48,326,634,6,8,2,3,0,0,1,0,0,0
1,9,8,3,4,0,0,22,0,0,0,-1--1--1,,1|(357,634)|
1,10,8,7,100,0,0,22,0,0,0,-1--1--1,,1|(295,634)|
12,11,48,206,316,8,8,0,3,0,0,-1,0,0,0
11,12,48,271,316,6,8,2,3,0,0,1,0,0,0
1,13,12,2,4,0,0,22,0,0,0,-1--1--1,,1|(302,316)|
1,14,12,11,100,0,0,22,0,0,0,-1--1--1,,1|(239,316)|
1,15,22,12,1,0,0,0,0,64,0,-1--1--1,,1|(287,351)|
1,16,1,8,1,0,0,0,0,64,0,-1--1--1,,1|(324,588)|
10,17,x Inventory,608,412,40,20,3,3,0,0,0,0,0,0
12,18,48,424,412,8,8,0,3,0,0,-1,0,0,0
1,19,21,18,4,0,0,22,0,0,0,-1--1--1,,1|(463,412)|
1,20,21,17,100,0,0,22,0,0,0,-1--1--1,,1|(537,412)|
11,21,48,500,412,6,8,34,3,0,0,1,0,0,0
10,22,d Demand,500,431,34,11,32,3,0,0,0,0,0,0
10,23,Supply Line,866,414,40,20,3,3,0,0,0,0,0,0
1,24,26,17,4,0,0,22,0,0,0,-1--1--1,,1|(690,417)|
1,25,26,23,100,0,0,22,0,0,0,-1--1--1,,1|(785,417)|
11,26,508,739,417,6,8,34,3,0,0,1,0,0,0
10,27,"q t-L Receiving",739,436,49,11,32,3,0,0,-1,0,0,0
12,28,48,1072,416,8,8,0,3,0,0,-1,0,0,0
1,29,31,23,4,0,0,22,0,0,0,-1--1--1,,1|(942,416)|
1,30,31,28,100,0,0,22,0,0,0,-1--1--1,,1|(1027,416)|
11,31,48,985,416,6,8,34,3,0,0,1,0,0,0
10,32,q Ordering,985,435,35,11,32,3,0,0,-1,0,0,0
1,33,32,27,1,0,0,0,0,64,0,-1--1--1,,1|(864,476)|
10,34,L lead time,858,526,36,11,0,3,0,0,0,0,0,0
1,35,34,27,1,0,0,0,0,64,0,-1--1--1,,1|(782,488)|
10,36,alpha Inertia,314,471,39,11,0,3,0,0,0,0,0,0
1,37,36,22,1,0,0,0,0,64,0,-1--1--1,,1|(402,465)|
10,38,"F t+1 Demand Forecast",750,309,75,11,0,3,0,0,0,0,0,0
10,39,F t Prior Forecast,906,237,40,20,3,3,0,0,0,0,0,0
12,40,48,758,239,8,8,0,3,0,0,-1,0,0,0
11,41,48,816,239,6,8,2,3,0,0,1,0,0,0
1,42,41,39,4,0,0,22,0,0,0,-1--1--1,,1|(844,239)|
1,43,41,40,100,0,0,22,0,0,0,-1--1--1,,1|(788,239)|
1,44,21,31,1,0,0,0,0,64,0,-1--1--1,,1|(730,351)|
1,45,38,31,1,0,0,0,0,64,0,-1--1--1,,1|(902,339)|
1,46,39,31,1,0,0,0,0,64,0,-1--1--1,,1|(961,278)|
1,47,34,32,1,0,0,0,0,64,0,-1--1--1,,1|(934,495)|
1,48,21,38,1,0,0,0,0,64,0,-1--1--1,,1|(578,345)|
1,49,38,41,1,0,0,0,0,64,0,-1--1--1,,1|(774,269)|
10,50,x0 Initial Inventory,608,483,58,11,0,3,0,0,-1,0,0,0
1,51,39,38,1,0,0,0,0,64,0,-1--1--1,,1|(866,285)|
10,52,alpha Inertia,632,253,48,11,0,2,0,3,-1,0,0,0,128-128-128,0-0-0,|12||128-128-128
1,53,52,38,0,0,0,0,0,64,0,-1--1--1,,1|(684,277)|
10,54,One Period,748,184,37,11,0,3,0,0,-1,0,0,0
1,55,54,41,0,0,0,0,0,64,0,-1--1--1,,1|(780,210)|
10,56,One Period,218,265,46,11,0,2,0,3,-1,0,0,0,128-128-128,0-0-0,|12||128-128-128
1,57,56,12,0,0,0,0,0,64,0,-1--1--1,,1|(242,288)|
10,58,"E[epsilon] Mean Disturbance",140,495,90,11,0,3,0,0,-1,0,0,0
10,59,One Period,322,697,46,11,0,2,0,3,-1,0,0,0,128-128-128,0-0-0,|12||128-128-128
1,60,59,8,0,0,0,0,0,64,0,-1--1--1,,1|(323,669)|
1,61,3,8,1,0,0,0,0,64,0,-1--1--1,,1|(370,667)|
1,62,2,12,1,0,0,0,0,64,0,-1--1--1,,1|(318,281)|
1,63,39,41,1,0,0,0,0,64,0,-1--1--1,,1|(852,201)|
1,64,58,1,0,0,0,0,0,0,0,-1--1--1,,1|(238,516)|
10,65,seed,154,571,16,11,0,3,0,0,-1,0,0,0
1,66,65,1,0,0,0,0,0,0,0,-1--1--1,,1|(218,561)|
10,67,"Var[epsilon] SD Disturbance",132,533,90,11,0,3,0,0,-1,0,0,0
1,68,67,1,0,0,0,0,0,0,0,-1--1--1,,1|(235,535)|
10,69,mu Initial Forecast,368,233,58,11,0,3,0,0,-1,0,0,0
10,70,One Period,1028,535,46,11,0,2,0,3,-1,0,0,0,128-128-128,0-0-0,|12||128-128-128
1,71,70,32,0,0,0,0,0,64,0,-1--1--1,,1|(1009,491)|
1,72,69,2,0,0,0,0,0,0,1,-1--1--1,,1|(368,264)|
1,73,50,17,0,0,0,0,0,0,1,-1--1--1,,1|(608,459)|
1,74,69,26,0,0,0,0,0,0,1,-1--1--1,,1|(555,325)|
1,75,69,39,1,0,0,0,0,0,1,-1--1--1,,1|(640,199)|
12,76,0,516,124,137,38,8,4,0,0,-1,0,0,0
Stephen C. Graves, Massachusetts Institute of Technology, A Single-Item Inventory Model for a Non-Stationary Demand Process, MSOM 1:1, 1999
12,78,0,515,40,68,28,8,4,0,0,-1,0,0,0
Replicated by Tom Fiddaman, Ventana Systems, 1999, from:
///---\\\
:GRAPH FLOWS
:TITLE Flows
:SCALE
:VAR d Demand
:VAR q Ordering
:VAR "q t-L Receiving"
:GRAPH DEMAND_VS_FORECAST
:TITLE Demand vs Forecast
:SCALE
:VAR d Demand
:VAR "F t+1 Demand Forecast"
:L<%^E!@
9:test
15:0,0,0,0,0,0
19:100,0
27:0,
5:x Inventory
24:0
25:0
26:0