to findintercept
 local "guess    ; Variable storing user's guess at intercept.
 local "betterguess  ; Variable storing computer's guess at intercept.

 ; Display the function.
 print [For the function shown below:]
 print []
 printout "function

 ; Prompt user for a guess at the intercept.
 type [Enter a guess at an x-intercept: ]
 make "guess readword
 print[]

 ; Use improve_guess procecdure several times to apply Newton's method.
 make "betterguess improve_guess improve_guess improve_guess :guess

 ; Display the improved guess.
 print sentence [I have used Newton's method to improve this guess to] ~
                word :betterguess ".

 ; Give the user information on how close this is to an intercept.
 print []
 print (sentence [The value of the function at] :guess [is] ~
        word (function :guess) ". )
 print (sentence [The value of the function at] :betterguess [is] ~
        word (function :betterguess) ". )
end

to function :value
 output :value * :value * :value - 8
end

to improve_guess :guess
 output :guess - (function :guess) / (slope :guess)
end

to slope :value
 output 3 * :value * :value
end