Feb. 4, 2011
pp. 258-259: Formatting errors that caused overprinting. It should read:
Then we need to add those two squares:
(define (distance-to-top-left the-point)
; the-point a posn
; (posn-x the-point) a number (x)
; (posn-y the-point) a number (y)
; (* (posn-x the-point) (posn-x the-point)) a number (x2)
; (* (posn-y the-point) (posn-y the-point)) a number (y2)
; (+ (* (posn-x the-point) (posn-x the-point))
; (* (posn-y the-point) (posn-y the-point))) a number (x2+y2)
...)
and finally square-root that, using sqrt
:
(define (distance-to-top-left the-point)
; the-point a posn
; (posn-x the-point) a number (x)
; (posn-y the-point) a number (y)
; (* (posn-x the-point) (posn-x the-point)) a number (x2)
; (* (posn-y the-point) (posn-y the-point)) a number (y2)
; (+ (* (posn-x the-point) (posn-x the-point))
; (* (posn-y the-point) (posn-y the-point))) a number (x2+y2)
(sqrt (+ (* (posn-x the-point) (posn-x the-point))
(* (posn-y the-point) (posn-y the-point))))
)