function?[result]?=?ARIMA_algorithm（data?Periodicity?ACF_P?PACF_Q?n）
m1?=?length（data）;
%the?number?of?raw?data
for?i?=?Periodicity+1:m1
????y（i-Periodicity）?=?data（i）-data（i-Periodicity）;
end
%eliminating?the?periodicity
w?=?diff（y）;
%first-order?differential?for?eliminating?the?Trending
m2?=?length（w）;
%the?number?of?data?after?first-order?differential
k?=?0;
%the?number?of?initial?exploration?models
for?i?=?0:ACF_P
????for?j?=?0:PACF_Q
????????if?i?==?0?&&?j?==?0
????????????continue
????????elseif?i?==?0
????????????ToEstMd?=?arima（‘MALags‘1:j‘Constant‘0）;
????????elseif?j?==?0
????????????ToEstMd?=?arima（‘ARLags‘1:i‘Constant‘0）;
????????else
????????????ToEstMd?=?arima（‘ARLags‘1:i‘MALags‘1:j‘Constant‘0）;
????????end
????????%specify?the?structure?of?the