I am having probability difficulties...HELP
Author Message
I am having probability difficulties...HELP

How can I simulate customer arrivals, in say a restaurant, using
a Negative Exponential Distribution (NED) in C?

Your help would be appreciated, greatly.

Fri, 16 Aug 1996 02:10:00 GMT
I am having probability difficulties...HELP

Quote:
>How can I simulate customer arrivals, in say a restaurant, using
>a Negative Exponential Distribution (NED) in C?

I'll just give some hints, since this looks like a homework problem.

If the probability of a customer arriving in a given period is
constant, then it is fairly easy to show that the probability that a
customer will arrive after t is

P(t) = (1/T) exp (-t/T)

where T is the mean time before a customer arrives.  Thus, in a
simulation, one selects a deviate from this distribution to represent
the time between a given point (say opening time or the arrival of the
previous customer) and the next customer.

To select a deviate t, make the change of variables

t = -T log (Tu)

so that

P(u) = u

Clearly, u is a uniform deviate on (0,1] -- err, I've just had a blank
on the notation, but I mean to exclude 0 and include 1.  You can
generate uniform deviates using rand() and RAND_MAX in <stdlib.h>, but
be careful to generate them on (0,1] and not [0,1), and then use log()
in <math.h> to generate a value of t.

Fri, 16 Aug 1996 14:13:23 GMT
I am having probability difficulties...HELP

: How can I simulate customer arrivals, in say a restaurant, using
: a Negative Exponential Distribution (NED) in C?

: Your help would be appreciated, greatly.

Instructors are getting more and more creative every 6 monnths.

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Student programmers have (*NULL) free time...
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Fri, 16 Aug 1996 16:14:17 GMT

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