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[Gärtner Bernd <>]

Dear William,

thanks for reporting this. We had been made aware of a similar issue recently 
which we are currently tracking down. I will see whether this one is related. 
I'll get back to you when we know more. As a quick fix (that worked in the 
other case), you might try to replace the equality constraint by a pair of 
inequality constraints.

Sorry for the inconvenience.

Best regards,
Bernd.

________________________________________
Von: William Taysom 
[]
Gesendet: Dienstag, 10. Januar 2012 16:13
Bis: 

Betreff: [cgal-discuss] Segmentation fault from Quadratic (and Linear) Program

Hello,

I recently found a small example quadratic program (actually the objective is 
linear) which causes a segmentation fault.  The basic setup is as follows and 
a complete test file is attached.

== qp_segault (excerpt) ==

const int X = 0;
const int Y = 1;
const int Z = 2;

Quadratic_program<NT> qp;

void set_row(int i, NT x, NT y, NT z, Comparison_result rel, NT b) {
        qp.set_a(X, i, x);
        qp.set_a(Y, i, y);
        qp.set_a(Z, i, z);
        qp.set_r(i, rel);
        qp.set_b(i, b);
}

int main() {
        // Just try to minimize X
        // though the objective function doesn't make a difference.
        qp.set_c(X, 1);

        set_row(0, 1, 1, 1,  EQUAL, 4);
        set_row(1, 1, 1, 1, LARGER, 4);
        set_row(2, 1, 0, 1, LARGER, 3);
        set_row(3, 1, 1, 0, LARGER, 3);

        qp.set_u(X, true, 2);

        Quadratic_program_solution<ET> sol;
        sol = solve_quadratic_program(qp, ET());
        std::cout << sol;
}

==

Pretty much any change to the problem setup removes the segfault, but changes 
to the objective function, solution function, number type, and options do not.

I'm new to CGAL, and I've been very pleased with the API so far.  I hope we 
can work together to find the root cause of this segfault.

Best regards,
William


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