functions: Add apply-tbf and apply-tbf/boolean.

functions.rkt

@@ -31,7 +31,9 @@
   [random-boolean-function/list (-> number? procedure?)]
   [tbf-w (-> tbf? (vectorof number?))]
   [tbf-θ (-> tbf? number?)]
-  [vector-boolean->01 (-> (vectorof boolean?) (vectorof (or/c 0 1)))]))
+  [vector-boolean->01 (-> (vectorof boolean?) (vectorof (or/c 0 1)))]
+  [apply-tbf (->* (tbf?) #:rest (listof (or/c 0 1)) (or/c 0 1))]
+  [apply-tbf/boolean (->* (tbf?) #:rest (listof boolean?) boolean?)]))
 
 (module+ test
   (require rackunit))
@@ -245,3 +247,33 @@
 (module+ test
   (test-case "boolean->0-1"
     (check-equal? (vector-boolean->01 #(#t #f #f)) #(1 0 0))))
+
+;;; Applies the TBF to its inputs.
+;;;
+;;; Applying a TBF consists in multiplying the weights by the
+;;; corresponding inputs and comparing the sum of the products to the
+;;; threshold.
+(define (apply-tbf tbf . inputs)
+  (any->01
+   (>
+    ;; The scalar product between the inputs and the weights
+    (for/sum ([x (in-list inputs)]
+              [w (in-vector (tbf-w tbf))])
+      (* x w))
+    (tbf-θ tbf))))
+
+(module+ test
+  (test-case "apply-tbf"
+    (define f1 (tbf #(2 -2) 1))
+    (check-equal? (tabulate/01 (λ (x y) (apply-tbf f1 x y)))
+                  '((0 0 0) (0 1 0) (1 0 1) (1 1 0)))))
+
+;;; Like apply-tbf, but takes Boolean values as inputs and outputs a
+;;; boolean value.
+(define (apply-tbf/boolean tbf . inputs)
+  (01->boolean (apply ((curry apply-tbf) tbf) (map any->01 inputs))))
+
+(module+ test
+  (define f1 (tbf #(2 -2) 1))
+  (check-equal? (tabulate/boolean (λ (x y) (apply-tbf/boolean f1 x y)))
+                '((#f #f #f) (#f #t #f) (#t #f #t) (#t #t #f))))