Hi All,

Gather-Update-Solve-Scatter (GUSS) (link:https://www.gams.com/latest/docs/S_GUSS.html)gives me a very good insight to solve multiple models with different parameters efficiently. However when I was going to implement my own model, it has some problems which I cannot figure out. I tried to solve one model with 64 different parameters, i.e.64 LPs via GUSS modeling like follows.

```
Set i /1*4/
j /1*3/
s /1*64/;
**** Scenario Data ****
parameter rhsy(s,j);
loop(s$(ord(s)<=16),
rhsy(s,'1') = 0;
);
loop(s$(ord(s)<=32 and ord(s)>16),
rhsy(s,'1') = 1;
);
loop(s$(ord(s)<=48 and ord(s)>32),
rhsy(s,'1') = 2;
);
loop(s$(ord(s)>49),
rhsy(s,'1') = 3;
);
loop(s$(ord(s)=1 or ord(s)=17 or ord(s)=32 or ord(s)=49),
rhsy(s,'2') = 0;
rhsy(s+1,'2') = 0;
rhsy(s+2,'2') = 0;
rhsy(s+3,'2') = 0;
);
loop(s$(ord(s)=5 or ord(s)=21 or ord(s)=36 or ord(s)=53),
rhsy(s,'2') = 1;
rhsy(s+1,'2') = 1;
rhsy(s+2,'2') = 1;
rhsy(s+3,'2') = 1;
);
loop(s$(ord(s)=9 or ord(s)=25 or ord(s)=40 or ord(s)=57),
rhsy(s,'2') = 2;
rhsy(s+1,'2') = 2;
rhsy(s+2,'2') = 2;
rhsy(s+3,'2') = 2;
);
loop(s$(ord(s)=13 or ord(s)=29 or ord(s)=44 or ord(s)=61),
rhsy(s,'2') = 3;
rhsy(s+1,'2') = 3;
rhsy(s+2,'2') = 3;
rhsy(s+3,'2') = 3;
);
loop(s$(ord(s)=1 or ord(s)=5 or ord(s)=9 or ord(s)=13 or ord(s)=17 or ord(s)=21 or ord(s)=25 or ord(s)=29 or ord(s)=33 or ord(s)=37 or ord(s)=41 or ord(s)=45 or ord(s)=49 or ord(s)=53 or ord(s)=57 or ord(s)=61),
rhsy(s,'3') = 0;
rhsy(s+1,'3') = 1;
rhsy(s+2,'3') = 2;
rhsy(s+3,'3') = 3;
);
display rhsy;
parameter prob(s);
prob(s)=0.25*0.25*0.25;
**** Model Data ****
Parameter coefy(i,j),x(i);
coefy('1','1')=40;
coefy('2','1')=45;
coefy('3','1')=32;
coefy('4','1')=55;
coefy('1','2')=24;
coefy('2','2')=27;
coefy('3','2')=19.2;
coefy('4','2')=33;
coefy('1','3')=4;
coefy('2','3')=4.5;
coefy('3','3')=3.2;
coefy('4','3')=5.5;
x('1') = 0; x('2') = 0; x('3') = 0; x('4') = 12;
equation obj,s2c2,s2d2;
variable objective;
positive variable y(i,j);
parameter rhsy2(j);
parameter Ds2c2p(s,i);
parameter Ds2d2p(s,j);
obj.. sum(i,sum(j,coefy(i,j)*y(i,j))) =e= objective;
s2c2(i).. sum(j,y(i,j))-x(i) =l= 0;
S2d2(j).. sum(i,y(i,j)) =g= rhsy2(j);
model mymodel /all/;
Set dict /s. scenario. ''
rhsy2. param. rhsy
s2c2. marginal. Ds2c2p
s2d2. marginal. Ds2d2p
/;
* GUSS Method
solve mymodel min objective use lp scenario dict;
$ontext
loop(s,
rhsy2(j) = rhsy(s,j);
solve mymodel use lp min objective;
Ds2c2p(s,i) = s2c2.m(i);
Ds2d2p(s,j) = s2d2.m(j);
);
$offtext
```

When compiled it, it gave an error saying “Symbol rhsy2 in dimension one in scenario dictionary has no data”. However, parameter rhsy is not empty.

If you delete the solving code of GUSS method, and the $ontext $offtext in the very end, which is going to solve the problem traditionally, it works fine.

I have gone through the GUSS documentation but found nothing useful for this issue. Does anybody have any idea?

BTW you might find the way I created the rhsy parameter a little bit tedious, but I do not have any other idea to do this. My another topic is relevant to this.

https://newforum.gams.com/t/aggregate-parameter-indices/2230/1

Best,

Gabriel