diff options
| -rw-r--r-- | coding-exercises/2/83/install-integer.rkt | 3 | ||||
| -rw-r--r-- | coding-exercises/2/83/install-rational.rkt | 2 | ||||
| -rw-r--r-- | coding-exercises/2/87.rkt | 42 | ||||
| -rw-r--r-- | shared/data-directed-programming.rkt | 2 |
4 files changed, 46 insertions, 3 deletions
diff --git a/coding-exercises/2/83/install-integer.rkt b/coding-exercises/2/83/install-integer.rkt index 2fabf3a..ca1ebb5 100644 --- a/coding-exercises/2/83/install-integer.rkt +++ b/coding-exercises/2/83/install-integer.rkt @@ -16,6 +16,7 @@ (put 'make 'integer (lambda (x) (tagme (make x)))) ;; methods (put 'add '(integer integer) (lambda (x y) (tagme (make (+ x y))))) + (put 'neg '(integer) (lambda (x) (tagme (- x)))) (put 'sub '(integer integer) (lambda (x y) (tagme (make (- x y))))) (put 'mul '(integer integer) (lambda (x y) (tagme (make (* x y))))) (put 'div '(integer integer) (lambda (x y) (tagme (make (/ x y))))) @@ -23,7 +24,7 @@ ;; sqrt and trig methods for complex nums (put 'sqr '(integer) sqr) (put 'sqrt '(integer) sqrt) - (put 'atan '(integer) atan) + (put 'atan '(integer integer) atan) (put 'cos '(integer) cos) (put 'sin '(integer) sin) ;; predicates diff --git a/coding-exercises/2/83/install-rational.rkt b/coding-exercises/2/83/install-rational.rkt index 96dcef1..73640b7 100644 --- a/coding-exercises/2/83/install-rational.rkt +++ b/coding-exercises/2/83/install-rational.rkt @@ -46,6 +46,8 @@ ;; interface (put 'add '(rational rational) (lambda (x y) (tagme (add-rat x y)))) + (put 'neg '(rational) + (lambda (rat) (tagme (neg-rat rat)))) (put 'sub '(rational rational) (lambda (x y) (tagme (sub-rat x y)))) (put 'mul '(rational rational) diff --git a/coding-exercises/2/87.rkt b/coding-exercises/2/87.rkt index d73093e..f368ed4 100644 --- a/coding-exercises/2/87.rkt +++ b/coding-exercises/2/87.rkt @@ -64,6 +64,17 @@ (term-list p2))) (error "Polys not in same var -- ADD-POLY" (list p1 p2)))) + (define (neg-poly poly) + (make-poly + (variable poly) + (map (lambda (term) + (make-term + (order term) + (apply-fn 'neg (coeff term)))) + (term-list poly)))) + (define (sub-poly p1 p2) + (add-poly p1 (neg-poly p2))) + (define (mul-term-by-all-terms t1 L) (if (empty-termlist? L) (the-empty-termlist) @@ -84,8 +95,17 @@ (mul-terms (term-list p1) (term-list p2))) (error "Polys not in same var -- MUL-POLY" (list p1 p2)))) + (define (polynomial-=zero? poly) + (define (rec term-list) + (cond ((empty-termlist? term-list) true) + ((not (apply-fn '=zero? (coeff (first-term term-list)))) false) + (else (rec (rest-terms term-list))))) + (rec (term-list poly))) + (put '=zero? '(polynomial) polynomial-=zero?) ;;interface (put 'add '(polynomial polynomial) (lambda (p1 p2) (tagme (add-poly p1 p2)))) + (put 'neg '(polynomial) (lambda (p) (tagme (neg-poly p)))) + (put 'sub '(polynomial polynomial) (lambda (p1 p2) (tagme (sub-poly p1 p2)))) (put 'mul '(polynomial polynomial) (lambda (p1 p2) (tagme (mul-poly p1 p2)))) (put 'make 'polynomial (lambda (var terms) (tagme (make-poly var terms)))) @@ -101,6 +121,26 @@ (list 3 test-real) (list 1 test-rat) (list 0 test-integer)))) +(define test-poly3 (make-polynomial 'x (list + (list 1 2) + (list 0 2)))) +((lambda () + (newline) + (display (add test-poly2 test-poly2)) + (newline) + (display (mul test-poly2 test-poly2)) + (newline) + (display (mul test-poly3 test-poly3)))) + +;;87 +(=zero? test-poly3) +(=zero? (make-polynomial 'x (list (list 1000 0)))) + +;; 88 +;; what is meant with negation here? Negation of a number? Making a negative number? +;; Guess that would be handy if we need to subtract a lot of terms. ((lambda () (newline) - (display (add test-poly2 test-poly2)))) + (display (sub test-poly1 test-poly3)) + (newline) + (display (sub test-poly1 test-poly2)))) diff --git a/shared/data-directed-programming.rkt b/shared/data-directed-programming.rkt index 4b4762c..92a7e14 100644 --- a/shared/data-directed-programming.rkt +++ b/shared/data-directed-programming.rkt @@ -246,4 +246,4 @@ (let ((raised-proc (get op (map type-tag raised-args)))) (if raised-proc (towerdrop (apply raised-proc (map contents raised-args))) - (error "Could not apply --" (list op args raised-args))))))))) + (error "Could not apply --" (list op raised-args))))))))) |