1		% (c) 2012 Lehrstuhl fuer Softwaretechnik und Programmiersprachen,
2		% Heinrich Heine Universitaet Duesseldorf
3		% This software is licenced under EPL 1.0 (http://www.eclipse.org/org/documents/epl-v10.html)
4
5		:- module(interval_calc,[interval_addition/3
6		,interval_subtraction/3
7		,interval_multiplication/3
8		,interval_negation/2
9		]).
10
11		:- use_module(module_information,[module_info/2]).
12		:- module_info(group,analysis).
13		:- module_info(description,'This module provides methods to calculate with interval expressions.').
14
15		:- use_module(inf_arith).
16
17		interval_addition(irange(Am,AM),irange(Bm,BM),irange(Cm,CM)) :-
18		Cm infis Am+Bm, CM infis AM+BM.
19		interval_subtraction(irange(Am,AM),irange(Bm,BM),irange(Cm,CM)) :-
20		Cm infis Am-BM, CM infis AM-Bm.
21		interval_multiplication(irange(Am,AM),irange(Bm,BM),irange(Cm,CM)) :-
22		MultExprs = [Am*Bm,Am*BM,AM*Bm,AM*BM],
23		get_min(MultExprs,Cm),
24		get_max(MultExprs,CM).
25		interval_negation(irange(Am,AM),irange(Cm,CM)) :-
26		CM infis -Am, Cm infis -AM.
27
28		get_min([A],Min) :- !, Min infis A.
29		get_min([A|Rest],Min) :-
30		get_min(Rest,Rmin), Min infis min(A,Rmin).
31		get_max([A],Max) :- !,Max infis A.
32		get_max([A|Rest],Max) :-
33		get_max(Rest,Rmax), Max infis max(A,Rmax).