SIMSCRIPT II.5 Programming Language

SIMSCRIPT II.5 Programming Language
(b) An additional attribute named TOTAL for the temporary entity JOB.
The tally variables may be used in statements such as:
for each JOB in QUEUE(MACHINE),
do
if TOTAL(JOB) le MAX.ALLOWED,
remove the JOB from QUEUE(MACHINE)
perform NEXT.JOB given JOB
always
loop
Statistical computations of a different sort are made when the word accumulate replaces tally.
These calculations introduce simulation time into the average, variance, and standard deviation calculations,
weighting the collected observations by the apparent length of simulation time for which
these values have held. Table 5-8 compares the tally and accumulate computations. To be concise,
some additional notation must be defined:
T L
The simulated time at which an accumulated variable was set to its current value
T 0
The simulated time at which accumulation starts
Accumulate and tally statements cannot both be declared for the same variable. A programmer
must decide whether a variable is time-dependent or not, normally a simple task, and specify one
or the other. An illustration of the use of the accumulate statement is given in the following example.
preamble
permanent entities
every MACHINE has a STATUS, a
PROCESSING.SPEED and owns a QUEUE
temporary entities
every JOB has a VALUE and belongs to a QUEUE
accumulate AVG.QUEUE as the mean
and MAX.QUEUE as the maximum of N.QUEUE
accumulate MACHINE.STATE as the mean of STATUS
end
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