SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
basic time unit is interpreted as microseconds, the phrase reads as, "in one and one-half microseconds
from now."
Many simulations represent activities in real time, where the time units commonly used are minutes,
hours, and days. Some standard conversion factors allow SIMSCRIPT II.5 to recognize these time
units. The standard units of time.v are presumed to mean days (e.g., 1.47 is one and forty-seven
one-hundredths days). The phrases:
in arithmetic expression days
in arithmetic expression minutes
in arithmetic expression hours
are understood to mean that the named event is to occur at time.v plus the specified number of
days, hours, or minutes. The word units can be used instead of days, and the word after substituted
for in. Conversions are made by taking the units of time.v as days and using two, real
mode, conversion variables, hours.v and minutes.v, initialized by the SIMSCRIPT II.5 system
to 24 and 60, respectively. These values may be changed at any time to reflect a different measurement
of simulated time.
If time is to be simulated in units of days, hours, and minutes, it can be convenient to reconvert absolute
values of time.v to these units. Three system functions described in table 5-2 provide this
capability. A simulation time of zero is assumed to correspond to the start of the first hour within
the first day of a week.
These functions may be useful in displaying results of a simulation, tracing simulation activity, or
in imposing realistic constraints on the execution of events in simulated time. Two examples illustrate
these uses:
1. A check to allow arrival events to occur only on weekdays or a Saturday:
if WEEKDAY.F(time.v) greater than 6,
reschedule this ARRIVAL at TRUNC.F(time.v)+1
always
2. A process trace statement put at the head of a process routine:
write WEEKDAY.F(time.v), HOUR.F(time.v) and MINUTE.F(time.v) as
"MACHINING ACTIVITY STARTS ON DAY", I 2,
"AT TIME", I 2, ":", I 2, /
A third kind of event scheduling uses the word now (or next, its synonym) in statements such as:
schedule an ARRIVAL now
Processes or events scheduled with a now phrase occur as soon as control passes back to the timing
routine. They precede any scheduled processes or events that may have the same scheduled time.
If two or more are scheduled to occur now, they are ranked on their priority if they are of differ-
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