Intellektual tizimlar

1.1.4. Opisaniye arifmeticheskix operasiy. V yazыke PROLOG ispolzuyetsya ryad vstroyennыx funksiy dlya vыchisleniya arifmeticheskix vыrajeniy, nekotorыye iz kotorыx perechislenы v tabl. 1.
Tablisa 1

Oboznacheniye	Tip operasii
>, <, =, >=, <=, <>	Operasii sravneniya
+, -, *, /	Arifmeticheskiye operasii
X mod Y	Ostatok ot deleniya X na Y
X div Y	Chastnoye ot deleniya X na Y
abs(X)	Absolyutnaya velichina chisla X
sqrt(X)	Kvadratnыy koren iz X
sin(X), cos(X), tan(X), arctan(X)	Trigonometricheskiye funksii
exp(X)	Vozvedeniye v stepen X
log(X)	Desyatichnыy logarifm chisla X
ln(X)	Naturalnыy logarifm chisla X

Dlya opisaniya lyubыx operasiy arifmetiki mojno takje ispolzovat sobstvennыye predikatы. Naprimer:

Programma 4
PREDICATES
add(integer,integer)
fadd(real,real)
maximum(real,real,real)
CLAUSES
add(X,Y):-Z=X+Y,write(“Sum= “,Z),nl.
fadd(X,Y):-Z=X+Y,write(“FSum= “,Z),nl.
maximum(X,X,X).
maximum(X,Y,X):- X>Y.
maximum(X,Y,Y):- XPredikatы PROLOGA ne mogut poyavlyatsya v arifmeticheskix vыrajeniyax. Yesli trebuyetsya, naprimer, peremennoy R prisvoit znacheniye, ravnoye bolshemu iz dvux vыrajeniy X i Y, umnojennomu na 3, to, ispolzuya predikat maximum, eto mojno zapisat tak:
maximum(X,Y,Z), R= 3*Z.
Vыchislit dlinu gipotenuzы po dlinam katetov pryamougolnogo treugolnika mojno s pomoщyu konstruksii:
gipotenuza(X,Y,Z):- Z = sqrt(X*X + Y*Y).