22a. Recursion Quiz Practice

Use define/contract for each function.

1. hawaiian-earring: number(stage) number(radius) -> image. Create stage circles with each successive circle 80% of the radius of the previous one.

   

2. double-ss: string -> string. Double each s appearing in the string.

    (check-expect (double-ss "The snake was silent.") 
                  "The ssnake wass ssilent.")
   

3. math-mess: number(start) number(end) -> number. For all of the numbers between start and end: add the squares of the even numbers, subtract the square roots of the odd numbers.

    (math-mess 10 10) => (* 10 10)
    (math-mess 11 11) => (- (sqrt 11))
    (math-mess 10 11) => (- (* 10 10) (sqrt 11))