urgent help with error 149

GAMS
1

I keep getting the error on the last 2 lines, but not the cost line and i dont really get why, any help would be much appreciated.

`Sets
i POSITIONS / P1, P2, P3, B, DG, V1, V2, V3, H, F /
;
alias(i,j)
;
…

Variables
X(i,j) wether node i and node j are connected [binary variable]
C total cost of the connections
Binary variable X
;
Equations
cost, connected, self;
cost… C =e= SUM[(i,j), X(i,j)*sqrt(sqr(CX(i)-CX(j))+sqr(CY(i)-CY(j)))*VC+FC]
;
connected… SUM[(j), X(i,j)] + SUM[(j), X(j,i)] =g= 1;
self… X(i,i) =e= 0;
…`

Ive been whatver i can find online but from the examples i can find i cant really find the issue

2

Hi,

You are not controlling the i index in the equations properly. For equation connected, which element(s) of i should be used. It is not clear from how you define the equation. Maybe this equation should be generated for all elements in i? Then you need to use i in the equation domain.

connected(i).. SUM[(j), X(i,j)] + SUM[(j), X(j,i)] =g= 1;

Same applies for equation self, but there you could also just get rid of the equation and fix the corresponding variables to zero.

X.fx(i,i) = 0;

In general, when sharing code, I suggest sharing the full code such that other forum users can reproduce what your are doing.

Best,
Fred