Club 100 Library - 415/939-1246 BBS
937-5039 NEWSLETTER, 932-8856 VOICE

This program downloads into 2450 bytes and takes 1880 bytes in BASIC.

In order to run this program, the user
must supply the following parameters:
 
 1) #cols....width of ocean in columns
 2) #rows....length of ocean
 3) #fish....initial number of fish
 4) #sharks..initial number of sharks
 5) fish breed...fish reproductive age
 6) shark breed...# meals required to
                  breed
 7) starve....# cycles a shark can live
              without eating a fish
 8) #attempts..shark hunting efficiency
 9) feed range...shark feeding range
10) sound (1=y)..1=sound, 0=silence
    (sound makes it easier to follow
    the action)

The fish, which appear as small diamonds on the screen, move about at random,
 eat plankton, and reproduce.  Aside from being shark-bait, that is the
extent of their activity.  Alas, they don't even have enough intelligence to
avoid a hungry shark.  Fortunately for them, however, the user has control of
the sharks' hunting efficiency.  The parameter, "feed range" limits the
distance from which they can make a kill.  For realism (and in the interest
of keeping the sharks lives exciting), 1 or 2 is recommended here.  The other
shark-controling factor, "# attempts", controls the number of times a shark
randomly looks (within the square defined by his "feeding range" limit)
 for a fish.  This can range from 1 up. The use of very large numbers in this
 parameter will slow the program down proportionately, as well as making it a
very hostile environment for the local variety of fish.
The sharks, of which only a fin is visible above the surface, also move
around randomly (one space at a time) - except when they see a fish, of course.
 
The simulation progresses with 2 passes of the ocean per cycle:  a move/feed
cycle and a reproduction/starvation
cycle.  At any time a lowercase "t" can be pressed and released to produce the
 current tallys of fish eaten, sharks starved, and the fixed run parameters. 
 These numbers will not come up until the completion of the current cycle so,
 in the case of large oceans, be patient.  After reading the tally
 screen, just press "enter" and the run will continue.

The best sets of parameters that I have
found have given extremely stable runs - one of which went 8 days
 before I cancelled it (to get my computer back!).  Now for the bad
 news... I'm not telling those parameters.

I'd be interested to know of any wild
 and crazy, yet stable, parameter sets to arise from anyones experimentation.

-Ray Yeargin 

P.S.  T200 users:  change the if
 statement in line 11 to read "IFK=39ANDP=15THEND(K,P)=638"
The "15" and "638" changes prevent writing into the last character of the
 screen & therefore scrolling and botching the screen.  If you don't make
this change, you must limit yourself to a "#cols" parameters of 39 and less.