题目内容：

lingo @for
我的LINGO程式码在@FOR的地方卡住了,希望大大可以帮我解答一下,万分感激,以下是程式码的部份
SETS:
SET_PT /1..2/:PT_i; Node i...J average production time/day;
SET_TiJ /1..2/:TiJ; Node i...J average transportation time/day;
SET_LT /1..2/:LT_i; Node i...J average lead time/day;
SET_HC /1..2/:HC_i; Node i...J average holding cost/day;
SET_X /1..2/:X_i; Node i...J/day;
ENDSETS
DATA:
D=20; mean deman/day;
SD=2; Std.Dev./day;
PT_i=4,7; Nodei...J average production time/day;
TiJ=0,3; Nodei...J average transportation time/day;
HC_i=2,3; Nodei...J average holding cost/day;
Z=1.65; Safety Factor;
P=10; Nodei...J average penalty cost/day;
ENDDATA
The objective Guaranteed Serviced Tiem;
MIN=seq1+seq2+seq3;
seq1=Z*HC_i(1)*SD*(LT_i(1)-X_i(1))^.5;
seq2=Z*HC_i(2)*SD*(LT_i(2)-X_i(2))^.5;
seq3=P*(LT_i(2)-X_i(2));
The constraints;
@FOR(LT_i(1)=PT_i(1));
@FOR(LT_i(1)>X_i(1));
@FOR(LT_i(2)>X_i(2));
@FOR(X_i(1)>0);
@FOR(X_i(2)>0);
END