Project:
 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 ``` ```; zeller's congruence (define (julian year month day) (let* ((a (quotient (- 14 month) 12)) (y (+ year 4800 (- a))) (m (+ month (* 12 a) -3))) (+ day (quotient (+ (* 153 m) 2) 5) (* 365 y) (quotient y 4) (- (quotient y 100)) (quotient y 400) (- 32045)))) (define (gregorian julian) (let* ((j (+ julian 32044)) (g (quotient j 146097)) (dg (modulo j 146097)) (c (quotient (* (+ (quotient dg 36524) 1) 3) 4)) (dc (- dg (* c 36524))) (b (quotient dc 1461)) (db (modulo dc 1461)) (a (quotient (* (+ (quotient db 365) 1) 3) 4)) (da (- db (* a 365))) (y (+ (* g 400) (* c 100) (* b 4) a)) (m (- (quotient (+ (* da 5) 308) 153) 2)) (d (+ da (- (quotient (* (+ m 4) 153) 5)) 122)) (year (+ y (- 4800) (quotient (+ m 2) 12))) (month (+ (modulo (+ m 2) 12) 1)) (day (+ d 1))) (values year month day))) (define-syntax assert (syntax-rules () ((assert expr result) (if (not (equal? expr result)) (for-each display `( #\newline "failed assertion:" #\newline expr #\newline "expected: " ,result #\newline "returned: " ,expr #\newline)))))) (define (zeller year month day) (let* ((m (if (< month 3) (+ month 10) (- month 2))) (yr (if (< month 3) (- year 1) year)) (d (modulo yr 100)) (c (quotient yr 100))) (list-ref '(Sunday Monday Tuesday Wednesday Thursday Friday Saturday) (modulo (+ day (quotient (- (* 13 m) 1) 5) d (quotient d 4) (quotient c 4) (* -2 c)) 7)))) (do ((i 2361331 (+ i 1))) ((= i 2726573)) (let-values (((year month day) (gregorian i))) (assert (list-ref '(Monday Tuesday Wednesday Thursday Friday Saturday Sunday) (modulo (julian year month day) 7)) (zeller year month day)))) (display (zeller 2010 10 8)) ```
 ```1 ``` `Friday`