I have made some chances and I believe now the only problem is making the
system reorder. Please any help would be great
test <- function(seed = 123456789, maxStock= 100, minStock =
20,t.max=1100,inventory =50)
{
LAST = t.max
START = 0
t.demand = START
t.supply = START
t.current = START
GetDemand<-function()
{
t.demand <<- t.demand + runif(1,min=0,max=5)
return(t.demand)
}
GetSupply <-function(){
if (inventory < minStock)
{
t.supply <<- t.supply + 1.0
}
else
t.supply <<- Inf
return(t.supply)
}
main <- function(seed)
{
if(seed > 0)
set.seed(seed)
index = 0
t.current = START #### Starting
Conditions
t.demand = START
t.supply = START
minStock = 20
maxStock = 100
inventory = 50
order_costs = 0
storage_costs = 0
sum = list(inventory = 50,order_costs = 0,storage_costs = 0)
while(index < LAST){
index = index + 1
t.demand = GetDemand() ### expected time to next sale
t.supply = GetSupply() ### expected time to arrival of order,
Infinity as
order has not been placed
t.next =min(t.demand,t.supply) ###next event either sale or supply is
the one with imminent arrival
k = maxStock - inventory
t.current = t.next -min(t.demand,t.max)
if(inventory > 0) {
storage_costs = (t.next-t.current)*0.10*inventory
}
if (inventory < minStock)
{ ###Need to
Order
k = maxStock - inventory
order_costs = 50 + 0.02*k
sum$order_costs = sum$order_costs + order_costs
t.supply = GetSupply()
}
if(t.next ==t.demand)
{
inventory <<- inventory - 1
####Sale made
sum$inventory = sum$inventory - 1.0
t.demand = GetDemand()
}
if(t.next == t.supply)
{
####Order Arrives
sum$inventory = sum$inventory + k
k = 0
t.supply = GetSupply()
}
if(inventory < maxStock)
{
k = maxStock - inventory
sum$storage_costs = sum$storage_costs + storage_costs
sum$order_costs = sum$order_costs + order_costs
}
}
options(digits = 5)
sis = list(Time = index,StorageCosts =sum$storage_costs,OrderCosts=
sum$order_costs,AverageCosts =((sum$order_costs +
sum$storage_costs)/index),Inventory = sum$inventory)
return(sis)
}
return(main(seed))
}
--
View this message in context:
http://r.789695.n4.nabble.com/Discrete-Event-Simulation-problem-tp4377276p4383464.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
