MLinExpr and LinExpr incompatibilities, how to avoid that?
AnsweredHi, I am working with MVars and MLinExpr and I know that those environments are currently not compatible with LinExpr and Vars. However, Gurobi automatically switches the type of one of my variables from MVar to Var. Specifically, in Python,
These are three of my variables:
import gurobipy as grb
zeta = model.addMVar(
shape=1,
lb=grb.GRB.INFINITY,
ub=grb.GRB.INFINITY,
name="zeta",
vtype=grb.GRB.CONTINUOUS
)
Z = model.addMVar(
shape=100,
vtype=grb.GRB.CONTINUOUS,
name="Z"
)
Y = model.addMVar(
shape=(50,100),
vtype=grb.GRB.CONTINUOUS,
name='Y'
)
model.addConstrs(
Z[s] >= a @ X  b @ Y[:, s]  zeta
for s in range(100)
)
And it raises the error:
GurobiError: Unsupported type (<class 'gurobipy.MLinExpr'>) for LinExpr addition argument

Hi Daniele,
We currently have a few issues with interactions between Var/LinExpr and MVar/MLinExpr. There were some fixes added to the most recent release (version 9.5.1) which should address your case. Could you please upgrade to version 9.5.1 and additionally rewrite your constraints as below?
model.addConstrs(
a @ X  b @ Y[:, s]  zeta  Z[s] <= 0
for s in range(100)
)Note  I'm assuming here that X is a 1D MVar (similar to Z) and a and b are 1D numpy arrays with compatible shapes for multiplying with X and Y[:, s].
Best regards,
Simon1 
Thank you Simon, now it works!
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