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Static filter Angle_3: now handle over/underflows

This commit is contained in:
Laurent Rineau 2011-11-28 14:52:43 +00:00
parent c9b29f87c7
commit fef3253301
1 changed files with 25 additions and 10 deletions
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35
Filtered_kernel/include/CGAL/internal/Static_filters/Angle_3.h
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@ -108,14 +108,19 @@ public:
if(maxrq < maxpq) std::swap(maxrq, maxpq); if(maxrq < maxpq) std::swap(maxrq, maxpq);
// then maxrq >= maxpq // then maxrq >= maxpq
// TODO: OVERFLOW and UNDERFLOW; // Protect against underflow in the computation of eps.
if (maxpq < 1e-146) /* sqrt(min_double/eps) */ {
if (maxpq == 0)
return RIGHT;
}
else if (maxrq < 7e153) /* sqrt(max_double / 3) */ {
double scal = pqx * rqx + pqy * rqy + pqz * rqz;
double scal = pqx * rqx + pqy * rqy + pqz * rqz; double eps = 1.6e-15 * maxpq * maxrq;
double eps = 7e-15 * maxpq * maxrq; if(scal > eps) return ACUTE;
if(scal < -eps) return OBTUSE;
if(scal > eps) return ACUTE; }
if(scal < -eps) return OBTUSE;
CGAL_BRANCH_PROFILER_BRANCH_2(tmp); CGAL_BRANCH_PROFILER_BRANCH_2(tmp);
} }
@ -127,15 +132,25 @@ public:
static double compute_epsilon() static double compute_epsilon()
{ {
typedef Static_filter_error F; typedef Static_filter_error F;
F t1 = F(1); // F t1 = F(1);
F f = ((t1 - t1) * (t1 - t1)) + // F f = ((t1 - t1) * (t1 - t1)) +
((t1 - t1) * (t1 - t1)) + // ((t1 - t1) * (t1 - t1)) +
((t1 - t1) * (t1 - t1)); // ((t1 - t1) * (t1 - t1));
F t1 = F(1, F::ulp()/2); // First translation
F f = t1*t1 + t1*t1 + t1*t1;
double err = f.error(); double err = f.error();
err += err * 2 * F::ulp(); // Correction due to "eps * m * m ". err += err * 2 * F::ulp(); // Correction due to "eps * m * m ".
std::cerr << "*** epsilon for Angle_3(Point_3, Point_3, Point_3) = " std::cerr << "*** epsilon for Angle_3(Point_3, Point_3, Point_3) = "
<< err << std::endl; << err << std::endl;
std::cerr << "\n"
<< "Now for underflow/overflows...\n"
<< " min_double/eps = "
<< std::numeric_limits<double>::min() / err << std::endl
<< " sqrt(min_double/eps) = "
<< CGAL::sqrt(std::numeric_limits<double>::min() / err) << std::endl
<< " sqrt(max_double/3) = "
<< CGAL::sqrt(std::numeric_limits<double>::max() / 3) << std::endl;
return err; return err;
} }