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Add a compare() for two rationals given as four values

This commit is contained in:
Andreas Fabri 2021-03-18 14:13:20 +01:00
parent be39ec02fa
commit 06f625a98e
1 changed files with 30 additions and 0 deletions
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30
Algebraic_foundations/include/CGAL/number_utils.h
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@ -324,6 +324,36 @@ NT approximate_sqrt(const NT& nt)
return approximate_sqrt(nt, Sqrt()); return approximate_sqrt(nt, Sqrt());
} }
template <class NT>
Comparison_result
compare(const NT& xnum, const NT& xden,
const NT& ynum, const NT& yden)
{
// No assumptions on the sign of den are made
// code assumes that SMALLER == - 1;
CGAL_precondition( SMALLER == static_cast<Comparison_result>(-1) );
int xsign = sign(xnum) * sign(xden) ;
int ysign = sign(ynum) * sign(yden) ;
if (xsign == 0) return static_cast<Comparison_result>(-ysign);
if (ysign == 0) return static_cast<Comparison_result>(xsign);
// now (x != 0) && (y != 0)
int diff = xsign - ysign;
if (diff == 0)
{
int msign = sign(xden) * sign(yden);
NT leftop = NT(xnum * yden * msign);
NT rightop = NT(ynum * xden * msign);
return compare(leftop, rightop);
}
else
{
return (xsign < ysign) ? SMALLER : LARGER;
}
}
CGAL_NTS_END_NAMESPACE CGAL_NTS_END_NAMESPACE
} //namespace CGAL } //namespace CGAL