61 lines
1.0 KiB
Plaintext
61 lines
1.0 KiB
Plaintext
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/*
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**********************************************************************
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*
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* CLP(R) Version 2.0 (Example Programs Release)
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* (C) Copyright, March 1986, Monash University
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*
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**********************************************************************
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*/
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%
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% This program finds a root of a transcendental function given an initial
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% guess. It uses the Steffensen algorithm.
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% The goal ?- go finds a root of
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%
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% 2
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% 1 - X
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%
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% given X = 1.7 as an initial guess, requiring that the solution give a value
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% no more than 0.0000005 from zero.
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getnext(X,NX):-
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NX = X - (F / G),
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eval(X,F),
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getg(X,G).
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getg(X,G):-
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G = (FF - F)/F,
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eval(X,F),
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eval(X+F,FF).
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eval(X,1 - X * X).
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small(X,E):-
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X < 0,
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(0-X) < E .
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small(X,E):-
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X >= 0,
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X < E .
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solve(I,E):-
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eval(I,F),
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small(F,E),
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printf("%10.8f\n",[I]).
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solve(I,E):-
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printf("%10.8f\n",[I]),
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getnext(I,X),
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solve(X,E).
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go:- solve(1.7,0.0000005).
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% Output:
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% 1.70000000
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% 0.44834437
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% 0.91953538
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% 0.99701354
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% 0.99999555
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% 1.00000000
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?- printf("\n>>> Sample goal: go/0\n", []).
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