练习2.48-练习2.51

1.练习2.48

(define (make-segment start end)  (cons start end))(define (start-segment seg)  (car seg))(define (end-segment seg)  (cdr seg))

2.练习2.49

(require (planet "sicp.ss" ("soegaard" "sicp.plt" 2 1))) (define one 1.0) (define origin (make-vect 0 0)) (define lower-right (make-vect one 0)) (define upper-left (make-vect 0 one)) (define upper-right (make-vect one one))(define (outline frame)  ((segments->painter (list (make-segment origin lower-right)                            (make-segment lower-right upper-right)                            (make-segment upper-right upper-left)                            (make-segment upper-left origin)))   frame))(define seg1 (make-segment origin upper-right))(define seg2 (make-segment upper-left lower-right))(define (diamond frame)  ((segments->painter (list (make-segment (make-vect 0 0.5) (make-vect 0.5 0))                            (make-segment (make-vect 0.5 0) (make-vect 0.99 0.5))                            (make-segment (make-vect 0.99 0.5) (make-vect 0.5 0.99))                            (make-segment (make-vect 0.5 0.99) (make-vect 0 0.5))))   frame))(define (wave frame)  ((segments->painter (list                      (make-segment (make-vect 0.4 1.0)      ; 头部左上                                    (make-vect 0.35 0.85))                      (make-segment (make-vect 0.35 0.85)    ; 头部左下                                    (make-vect 0.4 0.64))                      (make-segment (make-vect 0.4 0.65)     ; 左肩                                    (make-vect 0.25 0.65))                      (make-segment (make-vect 0.25 0.65)    ; 左手臂上部                                    (make-vect 0.15 0.6))                      (make-segment (make-vect 0.15 0.6)     ; 左手上部                                    (make-vect 0.0 0.85))                                            (make-segment (make-vect 0.0 0.65)     ; 左手下部                                    (make-vect 0.15 0.35))                      (make-segment (make-vect 0.15 0.35)    ; 左手臂下部                                    (make-vect 0.25 0.6))                                            (make-segment (make-vect 0.25 0.6)     ; 左边身体                                    (make-vect 0.35 0.5))                      (make-segment (make-vect 0.35 0.5)     ; 左腿外侧                                    (make-vect 0.25 0.0))                      (make-segment (make-vect 0.6 1.0)      ; 头部右上                                    (make-vect 0.65 0.85))                      (make-segment (make-vect 0.65 0.85)    ; 头部右下                                    (make-vect 0.6 0.65))                      (make-segment (make-vect 0.6 0.65)     ; 右肩                                    (make-vect 0.75 0.65))                      (make-segment (make-vect 0.75 0.65)    ; 右手上部                                    (make-vect 1.0 0.3))                      (make-segment (make-vect 1.0 0.15)     ; 右手下部                                    (make-vect 0.6 0.5))                      (make-segment (make-vect 0.6 0.5)      ; 右腿外侧                                    (make-vect 0.75 0.0))                                            (make-segment (make-vect 0.4 0.0)      ; 左腿内侧                                    (make-vect 0.5 0.3))                      (make-segment (make-vect 0.6 0.0)      ; 右腿内侧                                    (make-vect 0.5 0.3)))                     )   frame))

3.练习2.50

(define (flip-horiz-my painter)  ((transform-painter (make-vect 1.0 0.0)                      (make-vect 0.0 0.0)                      (make-vect 1.0 1.0))   painter))(define (contrarotate180 painter)  ((transform-painter (make-vect 1.0 1.0)                      (make-vect 0.0 1.0)                      (make-vect 1.0 0.0))   painter))(define (contrarotate270 painter)  ((transform-painter (make-vect 0.0 1.0)                      (make-vect 0.0 0.0)                      (make-vect 1.0 1.0))   painter))

4.练习2.51

(define (below-my painter1 painter2)  (let ((split-point (make-vect 0.0 0.5)))    (let ((paint-up            ((transform-painter (make-vect 0.0 0.0)                               (make-vect 1.0 0.0)                               split-point)             painter1))          (paint-down           ((transform-painter split-point                              (make-vect 1.0 0.5)                              (make-vect 0.0 1.0))            painter2)))    (lambda (frame)      (paint-up frame)      (paint-down frame)))))(paint (below-my einstein einstein))(paint (rotate90 (beside (rotate270 einstein) (rotate270 einstein))))

5.练习2.52

(define (wave frame)  ((segments->painter (list                      (make-segment (make-vect 0.4 1.0)      ; 头部左上                                    (make-vect 0.35 0.85))                      (make-segment (make-vect 0.35 0.85)    ; 头部左下                                    (make-vect 0.4 0.64))                      (make-segment (make-vect 0.4 0.65)     ; 左肩                                    (make-vect 0.25 0.65))                      (make-segment (make-vect 0.25 0.65)    ; 左手臂上部                                    (make-vect 0.15 0.6))                      (make-segment (make-vect 0.15 0.6)     ; 左手上部                                    (make-vect 0.0 0.85))                                            (make-segment (make-vect 0.0 0.65)     ; 左手下部                                    (make-vect 0.15 0.35))                      (make-segment (make-vect 0.15 0.35)    ; 左手臂下部                                    (make-vect 0.25 0.6))                                            (make-segment (make-vect 0.25 0.6)     ; 左边身体                                    (make-vect 0.35 0.5))                      (make-segment (make-vect 0.35 0.5)     ; 左腿外侧                                    (make-vect 0.25 0.0))                      (make-segment (make-vect 0.6 1.0)      ; 头部右上                                    (make-vect 0.65 0.85))                      (make-segment (make-vect 0.65 0.85)    ; 头部右下                                    (make-vect 0.6 0.65))                      (make-segment (make-vect 0.6 0.65)     ; 右肩                                    (make-vect 0.75 0.65))                      (make-segment (make-vect 0.75 0.65)    ; 右手上部                                    (make-vect 1.0 0.3))                      (make-segment (make-vect 1.0 0.15)     ; 右手下部                                    (make-vect 0.6 0.5))                      (make-segment (make-vect 0.6 0.5)      ; 右腿外侧                                    (make-vect 0.75 0.0))                                            (make-segment (make-vect 0.4 0.0)      ; 左腿内侧                                    (make-vect 0.5 0.3))                      (make-segment (make-vect 0.6 0.0)      ; 右腿内侧                                    (make-vect 0.5 0.3))                      (make-segment (make-vect 0.5 0.75)      ; 笑脸左                                    (make-vect 0.45 0.8))                      (make-segment (make-vect 0.5 0.75)      ; 笑脸右                                    (make-vect 0.55 0.8)))                     )   frame))(define (up-split painter n)  (if (= n 0)      painter      (let ((smaller (up-split painter (- n 1))))        (below painter (below smaller smaller)))))(define (right-split painter n)  (if (= n 0)      painter      (let ((smaller (right-split painter (- n 1))))        (beside painter (below smaller smaller)))))(define (beside-same-painter painter)  (beside painter painter))(define (below-same-painter painter)  (below painter painter))(define (corner-split painter n)  (if (= n 0)      painter      (let ((up (up-split painter (- n 1)))            (right (right-split painter (- n 1))))        (let ((top-left (beside-same-painter up))              (bottom-right (below-same-painter right))              (corner (corner-split painter (- n 1))))          (beside (below painter top-left)                  (below bottom-right corner))))))(define (square-list painter n)  (let ((quarter (corner-split (flip-horiz painter) n)))    (let ((half (beside (flip-horiz quarter) quarter)))      (below (flip-vert half) half))))