;;;; math-utils-test.scm  -*- Scheme -*-
;;;; Kon Lovett, Oct '22

(import test)

(test-begin "Math Utils")

;;;

(import math-utils)

;;

(define (fibonacci/naive n)
  (case n
    ((0) 0)
    ((1) 1)
    (else (+ (fibonacci/naive (- n 1)) (fibonacci/naive (- n 2)))) ) )

(test-group "seqs"
  (test 2 (average 1 3))
  (test 3 (average 1 3 5))
  (test 3 (average '(1 3 5)))

  (test "true fib" (fibonacci/naive 10) (fibonacci 10))
  (test "approx fib" (fibonacci/naive 10) (inexact->exact (floor (fibonacci* 10))))

  (test 3628800 (factorial 10))
  #;
  (factorial- a fall)
  #;
  (factorial+ a rise)

  (test 137/60 (harmonic 4))
)

(define (approx-points b e pts)
  (map (lambda (c)
         (cons (exact->inexact (car c))
               (exact->inexact (round (+ (* b (car c)) e)))))
       pts))

(test-group "stats"
  (define area-3ln (trapezoid (lambda (x) (* 3 (log x))) 3 4))

  (define some-pts '((0 . 0) (1 . 2) (2 . 4) (3 . 8) (4 . 16)))
  (define data-pts '((1.47 . 52.21) (1.50 . 53.12) (1.52 . 54.48)
                     (1.55 . 55.84) (1.57 . 57.20) (1.60 . 58.57)
                     (1.63 . 59.93) (1.65 . 61.29) (1.68 . 63.11)
                     (1.70 . 64.47) (1.73 . 66.28) (1.75 . 68.10)
                     (1.78 . 69.92) (1.80 . 72.19) (1.83 . 74.46)))
  (define data-pts/exact
         (map (lambda (x)
                (cons (inexact->exact (car x)) (inexact->exact (cdr x))))
              data-pts))

  (test-assert (procedure? area-3ln))
  (test 3.74781341992827 (area-3ln 10))
  (test 3.74802173521736 (area-3ln 10000))

  (test 9/2 (average 4 5))
  (test 9/2 (average '(4 5)))
  (test 9/2 (average 4 5 4 5))

  (test '(19/5 -8/5) (receive (least-squares some-pts)))
  ;exact since do not need fp~=
  (test '(1702812740636016600843530210081488/27790957638923528730017463330997
          -305560554657646811776139815548877388711888796291/7822459154182827706963815203832551052025004032)
        (receive (least-squares data-pts/exact)))
  #;
  (print (approx-points 1702812740636016600843530210081488/27790957638923528730017463330997
                        -305560554657646811776139815548877388711888796291/7822459154182827706963815203832551052025004032
                        data-pts/exact))

  #;
  (cross-ratio a b c d)

  (test 70 (binomial 8 4))
)

(test-group "interest"
  (test 1938.84 (compound-interest 0.043 4 6 1500))
)

(test-group "log-with-base"
  (define log256 (log-with-base 256))
  (test-assert (procedure? log256))
  (test "log/base 256" 9 (inexact->exact (round (log256 995972255318008407568))))
)

(test-group "coprime"
  (test-assert (coprime? 2 1))
  (test-assert (coprime? 3 1))
  (test-assert (coprime? 81 19))
  (test-assert (not (coprime? 1 1)))
  (test-assert (not (coprime? 9 3)))
)

;;;

(test-end "Math Utils")

(test-exit)