Eli Towle

Hi Jose, I wonder if this error is caused by these two lines: v = m.addVars(metabolites, name='v')m.addConstrs(v[j]>=LB[i]*(1-y[j]) for j in reactions for i in lb_reaction) The \( v \) variables ar...

Hi Jose, This error means that the key 'ACALD' was not defined for one of the variables or parameters used in that constraint family. Specifically, v['ACALD'], LB['ACALD'], or y['ACALD'] does not e...

Hi Jialin, Unfortunately not. Gurobi generates these cuts in the presolved model space. Gurobi does not expose the presolved model to the user, so you won't be able to see the cuts it generates. Th...

Hi Jose, Yes, setting the vtype argument of Model.addVar() to GRB.BINARY will make sure the newly created variable is binary. In Python, the full construction of a single constraint of this form wo...

Hi Bill, If we let \( x_1 \) and \( x_3 \) represent the integer "aux" variables and \( y \) represent the "boben" variable, the mathematical equivalent of this programmatic formulation is: $$\begi...

Hi Ronan, In case these are snippets of code you're running, there are a few small errors: The model struct should have a field "obj" instead of a field "c" For QP2, the "csense" field should be n...

Hi Ronan, I think this might just be a matter of writing the problem in the correct way to apply the optimality conditions. We can write your problem as: $$\begin{alignat}{2} \min_x\ &&  \frac{1}{2...

Hi, You can change the type of a variable by modifying the VType variable attribute. For example: import gurobipy as gpm = gp.Model()# Create binary variablex = m.addVar(vtype=gp.GRB.BINARY)m.updat...

Hi Ibtissam, This depends on how you import the gurobipy package. Specifically, if you use import gurobipy as gp then the function is used with gp.quicksum(). If you import gurobipy using from guro...

Hi Ronan, Could you clarify your question? Gurobi optimizes with respect to the objective \(x^\top Q x + c^\top x\), with no scaling of the \( Q \) matrix. A lot of theory for quadratic programming...