Mauer-Oats Classes > Intermediate CS > 20. Using Structures > 20. Review

20. Review

Write checks and follow the design process as you write these functions.

Move to parabola. Input any point, output a point on the graph of y=x^2. Find the output point by moving vertically up or down from the input point until you reach the graph of y=x^2.
```
to-parabola: posn(initial) -> posn
```
If you have time, make an animation that shows a gray circle where the mouse is and then connects that via a gray line to a blue circle on the parabola. You can use my 400x400 parabola image to see the whole parabola. (Read the code I used to make the parabola if you want.)

If you want to see an upward facing parabola in people coordinates, you should use the formula below:
```
(define (f x)
    (+ 200 (* -1/200 (- x 200) (- x 200))))
```
Input a color, output a new color.
```
mix-color: color -> color
```
- output red is twice the input amount of green
- output green is the average of the input red, green, and blue
- output blue is 50 units less than half of the red input
Hot-Cold. Take in a posn and output a color. The color will depend on the distance of the point from (100,200).
- distance < 100: pure red
- distance > 355: pure yellow
- in between: red is 255 minus distance, green is distance minus 100, blue is 0
```
hot-cold: posn -> color
```