Convex function or not?

1

Dear all

I am trying form the linear programming relation of this article(“Budget-Constrained Auctions with Heterogeneous Items”)'s LP2.

It bring the constrains with the Myerson’s Lemma(Virtual Valuation).
link text 

cvx_begin
variable X(Bidder,Item)
PartOfDemand=sum(Parameter_g.*X,2);
PartOfBudget=sum(((Parameter_g.*VirtualValuation).*X),2);
PartOfSold=sum(Parameter_g.*X,1);
maximize sum(sum((Parameter_g.*VirtualValuation).*X))
subject to 
for i=1:Bidder
   PartOfDemand(i) <=Demand(i)
end
for i=1:Bidder
   PartOfBudget(i) <=Budget(i)
end
for j=1:Item
   PartOfSold(j) <=1
end
for i=1:Bidder
    for j=1:Item
    0<=  X(i,j) <=1 
    end
end
cvx_end

Is that a convex function ??

2

As we say in the FAQ), if you don’t know your model is convex, then CVX is not your tool, and this is not your forum. But you already seem to know this is a linear program, so what are you asking exactly?