![]() ![]() ![]() This program can process only factorials up to 12!, since trying to calculate 13! causes an integer overflow. After this factorials are returned and printed in increasing order of N. With each call of recursion N is decremented until it reaches 0. An Example Prolog Program Introduction When I started learning Prolog, I thought that the interactive console was great for trying things out and running queries real time, but I noticed an overall lack of instruction out there on writing a menu driven program that will take input. Visual Prolog provides a built-in construction, list comprehension. When the main program runs, factorial is called exactly once, for N=12. For example if X is connected to Z and Z List is a list containing all elements of. The second clause factorial(N,F) recursively calculates F1 as factorial of N-1, assigns N*F1 to return variable F and prints the result. After this the return variable F is set to 0! = 1 and the result of the clause is printed. The first rule in this clause is !, a so-called cut, which prevents backtracking to second clause factorial(N,F) and thus ensures that there is only one solution to the call. We don’t use memoization to store already calculated numbers, so this. Here we define two new predicates fibonacci(N,F) to calculate Nth Fibonacci number and loop(N) to output it. Visual Prolog searches the clauses for matching call in the order of their appearance in the code, so if first argument is zero, it starts with first clause factorial(0,F). Create a new project with UI Strategy Console and replace contents of files main.cl and main.pro with given code. There are two possible matches for each call of factorial - with zero or arbitrary first argument. In main.pro the actual description of newly specified predicate takes place. Keyword procedure describes the behavior of predicate, indicating that is will always succeed with only one solution, so no backtracking is required. specifies that factorial is a predicate of arity 2, with known first and unknown second argument. In main.cl the only added line factorial : (integer N, integer F) procedure (i,o). Create a new project with UI Strategy “Console” and replace contents of files main.cl and main.pro with given code. ![]()
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