**THIS CODE WAS WRITTEN FOR THE CONSTRAINT-BASED MODELING WORKSHOP J.REED (1/2008)
*REACTIONS
* v1: A -> B
* v2: B -> C
* b1:   -> A
* b2: B ->
* b3: C ->

sets
metabolites /A,B,C,D/
reactions /v1,v2,b1,b2,b3/;

parameters
c(reactions)
S(metabolites,reactions)
/A.v1 -1
B.v1 1
A.v2 -1
C.v2 1
A.b1 1
B.b2 -1
C.b3 -1/;

variables
v(reactions)
Z;

equations
massbalance(metabolites) S.v = 0
objectivefunction        Z=c.v ;

massbalance(metabolites).. sum(reactions, S(metabolites,reactions)*v(reactions))=e=0;
objectivefunction.. Z=e=sum(reactions,c(reactions)*v(reactions));

*Place lower bounds of 0 for all fluxes
v.lo(reactions)=0;
*Place upper bounds of 10 for all fluxes
v.up(reactions)=10;
*Define c, without this c is defaulted as being all zeros
c('v1')=1;

model FBA /all/;
solve FBA using lp maximizing Z;