TARGET



This program was inspired by the computer programs Green Globs and Algebra

Arcade.  In addition to the main program, there are three subroutines,

TARGDRAW, TARGHIT, and TARGCHK.



The object of the game is to write the equation of a function that hits as

many of the targets as possible.  Initially, there are 10 targets on the

screen, and they are graphed in the window [-9.4,9.4]x[-6.2,6.2].  When your

function hits one or more of them, they disappear.  You then take additional

"turns" by writing new functions until all ten targets are gone.



When you enter a function, do not type the Y=, only the expression that

follows that equal sign.  After you enter the function, you are asked if you

want to practice.  If you say yes, you will be able to see your graph in

relationship to the targets and adjust your function accordingly.  However,

only one practice is allowed per turn.



You are also asked whether your function needs checking.  Checking is required

of any function that is undefined in [-9.4,9.4].  For example, functions like

#195#x, log(x), and 1/x need checking.  Checking slows the graphing, so you

have the option of turning it off.  (Checking is not required of practice

functions, so you are not asked about checking when you practice.)



Scoring: you get 200 points if you hit one target, 300 points per target if

you hit two, 400 points per target if you hit three, etc.  However, your score

for a given function is reduced by 200 points if you choose to practice before

you enter the function.



Note that the program does not connect points as it graphs.  As a result, a

very steep portion of a graph may miss a target you expect to hit.  However,

this method of graphing has a major advantage--you cannot clear the entire

screen with a function like 6sin(100x).



Also note that occasionally two targets overlap, which means that one is

shielding the other.  It can be difficult to hit both targets when one is

shielding the other.  Can you do it?



The author of this program can be contacted by email at g.froelich@comap.com. 

The program appears in Consortium 59, copyright 1996,  COMAP, 57 Bedford

Street Suite 210, Lexington MA 02173, 617-862-7878.  The program can be used

by educators in classes and workshops, but should not be used in any other way

without COMAP's permission.