Gurobi solver in matlab

Question

I want to use Gurobi solver in Matlab, but I don't know how to calculate the required matrices (qrow and qcol).

For your reference I am copying the example provided in documentation.

0.5 x^2 - xy + y^2 - 2x - 6y

subject to

x + y <= 2
-x + 2y <= 2, 2x + y <= 3, x >= 0, y >= 0
c = [-2 -6]; % objective linear term

objtype = 1; % minimization

A = sparse([1 1; -1 2; 2 1]); % constraint coefficients
b = [2; 2; 3]; % constraint right-hand side
lb = []; % [ ] means 0 lower bound
ub = []; % [ ] means inf upper bound
contypes = '$<<
vtypes = [ ]; % [ ] means all variables are continuous
QP.qrow = int32([0 0 1]); % indices of x, x, y as in (0.5 x^2 - xy + y^2); use int64 if sizeof(int) is 8 for you system

QP.qcol = int32([0 1 1]); % indices of x, y, y as in (0.5 x^2 - xy + y^2); use int64 if sizeof(int) is 8 for you system

QP.qval = [0.5 -1 1]; % coefficients of (0.5 x^2 - xy + y^2)

Does it mean that if I have 4 decision variables than i should use 0,1,2,3 as indices for my decision variables x_1, x_2, x_3, x_4.?

Thanks

Note: I tried to use mathurl.com but I don't get how to write in proper format show that it will appear as latex text. Sorry for the notation.

Answer 1

This seems to be your reference. However your question seems to relate different example. You may need to show that one.

Anyway according Gurobi documentation:
The quadratic terms in the objective function should be specified by opts.QP.qrow, opts.QP.qcol, and opts.QP.qval, which correspond to the input arguments qrow, qcol, and qval of function GRBaddqpterms. They are all 1D arrays. The first two arguments, qrow and qcol, specify the row and column indices (starting from 0) of 2nd-order terms such as and . The third argument, qval, gives their coefficients.

So the answer is yes use indicies [0 1 2 3] for your decision variables x0, x1, x2, x3.