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Fix: initialize facet to -1 in line_positive_intersect to prevent undefined behavior #457

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Fix: initialize facet to -1 in line_positive_intersect to prevent undefined behavior #457

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2616ee7
Fix: initialize facet to -1 in line_positive_intersect to prevent UB
Dev-sh21 Feb 23, 2026
cd71148
ghmc sig match
Dev-sh21 Mar 12, 2026
d62ebee
Merge branch 'fix/gaussian-hmc-api-mismatch' into fix/uninit-facet-li…
Dev-sh21 Mar 12, 2026
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8 changes: 4 additions & 4 deletions include/convex_bodies/hpolytope.h
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Original file line number Diff line number Diff line change
Expand Up @@ -388,7 +388,7 @@ class HPolytope {
NT min_plus = std::numeric_limits<NT>::max();
NT max_minus = std::numeric_limits<NT>::lowest();
VT sum_nom;
int m = num_of_hyperplanes(), facet;
int m = num_of_hyperplanes(), facet = -1;

Ar.noalias() = A * r.getCoefficients();
sum_nom = b - Ar;
Expand Down Expand Up @@ -432,7 +432,7 @@ class HPolytope {
NT mult;
//unsigned int i, j;
unsigned int j;
int m = num_of_hyperplanes(), facet;
int m = num_of_hyperplanes(), facet = -1;

Ar.noalias() += lambda_prev*Av;
sum_nom = b - Ar;
Expand Down Expand Up @@ -546,7 +546,7 @@ class HPolytope {
NT lamda = 0;
NT inner_prev = params.inner_vi_ak;
VT sum_nom;
int m = num_of_hyperplanes(), facet;
int m = num_of_hyperplanes(), facet = -1;
int skip = params.facet_prev;

Ar.noalias() += lambda_prev*Av;
Expand Down Expand Up @@ -649,7 +649,7 @@ class HPolytope {

NT lamda = 0;
VT sum_nom;
int m = num_of_hyperplanes(), facet;
int m = num_of_hyperplanes(), facet = -1;
int skip = params.facet_prev;

Ar.noalias() += lambda_prev*Av;
Expand Down
14 changes: 12 additions & 2 deletions include/random_walks/gaussian_ball_walk.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ struct Walk
}

Walk (Polytope& P, Point const& p, NT const& a,
RandomNumberGenerator &rng)
RandomNumberGenerator &rng) : _a_i(a)
{
_delta = compute_delta(P, a);
}
Expand All @@ -62,12 +62,21 @@ struct Walk
Point const& p,
NT const& a,
RandomNumberGenerator &rng,
parameters const& params)
parameters const& params) : _a_i(a)
{
_delta = params.set_delta ? params.m_L
: compute_delta(P, a);
}

template<typename BallPolytope>
inline void apply(BallPolytope const& P,
Point &p,
unsigned int const& walk_length,
RandomNumberGenerator& rng)
{
apply(P, p, _a_i, walk_length, rng);
}

template<typename BallPolytope>
inline void apply(BallPolytope const& P,
Point &p, // a point to start
Expand Down Expand Up @@ -100,6 +109,7 @@ struct Walk

private :
NT _delta;
NT _a_i;
};

};
Expand Down
18 changes: 15 additions & 3 deletions include/random_walks/gaussian_hamiltonian_monte_carlo_exact_walk.hpp
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Expand Up @@ -9,6 +9,7 @@
#define RANDOM_WALKS_GAUSSIAN_EXACT_HMC_WALK_HPP

#include "sampling/sphere.hpp"
#include "random_walks/compute_diameter.hpp"



Expand Down Expand Up @@ -62,7 +63,7 @@ struct Walk
::template compute<NT>(P);
_omega = std::sqrt(NT(2) * a_i);
_rho = 100 * P.dimension(); // upper bound for the number of reflections (experimental)
initialize(P, p, a_i, rng);
initialize(P, p, rng);
}

template <typename GenericPolytope>
Expand All @@ -74,7 +75,7 @@ struct Walk
::template compute<NT>(P);
_omega = std::sqrt(NT(2) * a_i);
_rho = 100 * P.dimension(); // upper bound for the number of reflections (experimental)
initialize(P, p, a_i, rng);
initialize(P, p, rng);
}

template
Expand All @@ -86,6 +87,18 @@ struct Walk
NT const& a_i,
unsigned int const& walk_length,
RandomNumberGenerator &rng)
{
apply(P, p, walk_length, rng);
}

template
<
typename GenericPolytope
>
inline void apply(GenericPolytope const& P,
Point& p,
unsigned int const& walk_length,
RandomNumberGenerator &rng)
{
unsigned int n = P.dimension();
NT T;
Expand Down Expand Up @@ -198,7 +211,6 @@ private :
>
inline void initialize(GenericPolytope const& P,
Point const& p,
NT const& a_i,
RandomNumberGenerator &rng)
{
unsigned int n = P.dimension();
Expand Down
21 changes: 18 additions & 3 deletions include/random_walks/gaussian_rdhr_walk.hpp
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Expand Up @@ -80,13 +80,25 @@ struct Walk
typedef typename Polytope::PointType Point;
typedef typename Point::FT NT;

Walk(Polytope&, Point const&, NT const&, RandomNumberGenerator&)
Walk(Polytope&, Point const&, NT const& a, RandomNumberGenerator&) : _a_i(a)
{}

Walk(Polytope&, Point const&, NT const&, RandomNumberGenerator&,
parameters&)
Walk(Polytope&, Point const&, NT const& a, RandomNumberGenerator&,
parameters&) : _a_i(a)
{}

template
<
typename BallPolytope
>
inline void apply(BallPolytope const& P,
Point &p,
unsigned int const& walk_length,
RandomNumberGenerator &rng)
{
apply(P, p, _a_i, walk_length, rng);
}

template
<
typename BallPolytope
Expand All @@ -110,6 +122,9 @@ struct Walk
chord_random_point_generator_exp(lower, upper, a_i, p, rng);
}
}

private:
NT _a_i;
};

};
Expand Down
4 changes: 2 additions & 2 deletions include/sampling/random_point_generators.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,7 @@ struct GaussianRandomPointGenerator
Walk walk(P, p, a_i, rng);
for (unsigned int i=0; i<rnum; ++i)
{
walk.apply(P, p, a_i, walk_length, rng);
walk.apply(P, p, walk_length, rng);
policy.apply(randPoints, p);
}
}
Expand Down Expand Up @@ -184,7 +184,7 @@ struct GaussianRandomPointGenerator

for (unsigned int i=0; i<rnum; ++i)
{
walk.apply(P, p, a_i, walk_length, rng);
walk.apply(P, p, walk_length, rng);
policy.apply(randPoints, p);
}
}
Expand Down