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bug #977: avoid division by 0 in normalize() and normalized().

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This commit is contained in:
Gael Guennebaud
2016-01-21 20:43:42 +01:00
parent 7cae8918c0
commit ee37eb4eed
2 changed files with 25 additions and 3 deletions
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19
Eigen/src/Core/Dot.h
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@@ -102,7 +102,10 @@ inline typename NumTraits<typename internal::traits<Derived>::Scalar>::Real Matr
return numext::sqrt(squaredNorm());
}
/** \returns an expression of the quotient of *this by its own norm.
/** \returns an expression of the quotient of \c *this by its own norm.
*
* \warning If the input vector is too small (i.e., this->norm()==0),
* then this function returns a copy of the input.
*
* \only_for_vectors
*
@@ -114,19 +117,29 @@ MatrixBase<Derived>::normalized() const
{
typedef typename internal::nested_eval<Derived,2>::type _Nested;
_Nested n(derived());
return n / n.norm();
RealScalar z = n.squaredNorm();
// NOTE: after extensive benchmarking, this conditional does not impact performance, at least on recent x86 CPU
if(z>RealScalar(0))
return n / numext::sqrt(z);
else
return n;
}
/** Normalizes the vector, i.e. divides it by its own norm.
*
* \only_for_vectors
*
* \warning If the input vector is too small (i.e., this->norm()==0), then \c *this is left unchanged.
*
* \sa norm(), normalized()
*/
template<typename Derived>
inline void MatrixBase<Derived>::normalize()
{
*this /= norm();
RealScalar z = squaredNorm();
// NOTE: after extensive benchmarking, this conditional does not impact performance, at least on recent x86 CPU
if(z>RealScalar(0))
derived() /= numext::sqrt(z);
}
//---------- implementation of other norms ----------