Average Printing time

John_in_Parrish said:

A hypothetical program computes for 3 seconds then outputs a variable length record to be printed. The printer takes from 0.75 to 4.75 seconds (average time is 2.75 seconds) to print each output record. (Use a random number generator)

The hypothetical program loops 500 times for each case of software buffers (0, 1, 2, 3, 4, 5, 10, 25, and 100 software output buffers). Calculate the AVERAGE time for the program to “virtually compute and print” a record from the 500 records, for EACH of the 9 choices of buffer. Plot the results

The way I have the problem set up is (3 + avg time) / # of buffers. When I go to plot it though it makes sense for the buffers 1 - 100 but not the 0 buffer since it is divided by 0. So I am assuming I am setting this problem up incorrectly. It is a programing question I have no problem with the programing part just need some help getting the mathematical formula for the problem. Thanks in advance for your help,

John

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DrPhil said:

Since it says "virtually" and "use a random number generator," this is a simulation problem, NOT a "find the formula" problem. We usr the Monte Carlo technique to integrate problems where there is a difficult correlation between variables. In this problem, the correlation is that printing from the buffer is simultaneous with the computation.

I picture a master clock time variable, initialized to 0
You will also need a software buffer array with maximum dimension determined as a parameter (for nine different cases), all initialized to 0 -- what this array will actually contain it the printer time for that buffered output. You will also need to keep track of which buffer is currently being printed. Maybe a flag for "buffers full" (which would always be true if there are no buffers).

After initialization, make a loop for 500 times.
add 3 to the master clock for compute time.
Look at the buffer.. if the currently printing buffer is greater than 3 seconds, subtract 3;
..........................iif less than 3, set to 0, advance to next buffer, subtract whatever is left of 3 from that one
...........................if no unprinted buffers left, set index to 0
use random number to find print time for next output
Look at the buffer...if no buffer available, advance master clock by the time in the current buffer
...........................if there is room in the buffers, store the print time
[If max number of buffers =0, treat as special case]

After you finish the loop 500 times, you will have to flush any records still in buffers, by adding all of the remaining times to the master clock.

The final number in the master clock is the total time. Divide by 500 to get the average.

I didn't write any specific code, because I don't know what language you are using. BTW, my profession is writing Monte Carlo simulation codes for neutron scattering instrument design. My language of choice is Fortran.

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John_in_Parrish said:

AM I even close with this?

def main():
buffer= [0,1,2,3,4,5,10,25,100]
time= random.uniform(0.75,4.75)+3
sum=0
dict_of_buffers = {}
for i in range (1, 500):
sum = sum + time;
average= sum/1500
for buffer in range(0,1,2,3,4,5,10,25,100):
print("For Buffer",buffer,",the average time is",average,".")
dict_of_buffers[buffer] = average

Click to expand...

for buffer in range(0,1,2,3,4,5,10,25,100):
        [all the meat of the program]
    print("For Buffer",buffer,",the average time is",average,".")
end for (or some such loop closer?)

    sum = 0
    for i in range (1, 500):
        sum = sum+3
        print_time= random.uniform(0.75,4.75)
            [have to deal with the print queue]
    end for

        sum = sum + print_time - 3