;; Unicalc test cases

(load "a02.scm")

;; Function close-enough is meant to test whether two inexact quantites
;; have a relative difference that is within the specified tolerance.
;; This is used in cases where answers might not match exactly.


(define tolerance 1e-6)

(define (relative-error x y)
  (cond ((= x y) 0)
        ((not (= x 0)) (/ (abs (- x y)) x))
        (else (/ (abs (- x y) y)))))

(define (close-enough Quantity1 Quantity2)
  (and (equal? (rest Quantity1) (rest Quantity2))
       (< (relative-error (first Quantity1) (first Quantity2) ) tolerance)))


(test (normalize-unit 
       'second) 
       '(1 (second)()))

(test (close-enough (normalize-unit 'gram) '(0.001 (kg) ())) #t)

(test (normalize-unit 
       'kilometer) 
       '(1000 (meter) ()))

(test (normalize-unit
       'day) 
       '(86400 (second) ()))

(test (normalize-unit
       'newton) 
       '(1 (kg meter) (second second)))

(test (close-enough 
       (normalize 
        '(1 (mile)(hour))) 
        '(0.447031923888 (meter) (second))) #t)

(test (close-enough 
       (normalize 
        '(1e6 (pound)(mile mile))) 
        '(0.1751393211439157 (kg) (meter meter))) #t)

(test (normalize 
       '(1 (newton meter)(second))) 
       '(1 (kg meter meter) (second second second)))

(test (normalize 
       '(1 (volt)())) 
       '(1 (kg meter meter) (ampere second second second)))


(test (close-enough 
       (multiply (normalize '(1 (foot) ())) (normalize '(1 (acre) ()))) 
       '(1233.414987438996 (meter meter meter) ())) #t)

(test (multiply '(1 () ()) '(1 (kg meter)(second))) 
      '(1 (kg meter)(second)))

(test (multiply '(1 (chicken) (meter meter)) 
                '(100 (meter meter) ())) '(100 (chicken) ()))

(test (close-enough (multiply (normalize '(100 (tadpole) (gallon))) 
                              '(1 (meter meter meter) ())) 
                    '(26418.63702726775 (tadpole) ())) #t)


(test (close-enough (divide (normalize '(1 (yard)())) 
                            (normalize '(1 (foot)())))
                    '(3.0 ()())) #t)
                   
(test (close-enough (divide (normalize '(1 (mile)())) 
                            (normalize '(1 (foot)()))) 
                    '(5280.0 () ())) #t)

(test (close-enough (divide (normalize '(1 (torr) ())) (normalize '(1 (atmosphere)()))) 
                    '(0.0013157894736842105 () ())) #t)

(tester 'show)