Standard deviation


Example how to count standard deviation of list elements

Source: PROLOG str. 190 Wydawnictwo PLJ Warszawa 1991 ISBN 83-85190-63-5


Program source code:


sred(L, Sr) :- suma(L, S, 0, I, 0), Sr is S/I.
suma([], Sum, Sum, Ilosc, Ilosc).
suma([H|T], Sum, Sum1, Ilosc, Ilosc1) :- Nilosc is Ilosc + 1,
Nsuma is Sum1 + H, suma(T, Sum, Nsuma, Ilosc, Nilosc).
wari(L, W) :- sred(L, Sr), rozn2(L, H, Sr), suma(H, Suma, 0, Ilosc, 0),
W is Suma/Ilosc.
rozn2([], [], _).
rozn2([H|T], [R|T1], Sr) :- R is (H - Sr)*(H - Sr), rozn2(T, T1, Sr).
odch(L, O) :- wari(L, War), O is sqrt(War).
test :- odch([1, 2, 3, 4, 5], O).


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