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bug #1004: improve accuracy of LinSpaced for abs(low) >> abs(high).

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This commit is contained in:
Gael Guennebaud
2016-11-02 11:34:38 +01:00
parent 598de8b193
commit a07bb428df
2 changed files with 61 additions and 9 deletions
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31
Eigen/src/Core/functors/NullaryFunctors.h
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@@ -43,12 +43,17 @@ template <typename Scalar, typename Packet>
struct linspaced_op_impl<Scalar,Packet,/*IsInteger*/false>
{
linspaced_op_impl(const Scalar& low, const Scalar& high, Index num_steps) :
m_low(low), m_high(high), m_size1(num_steps==1 ? 1 : num_steps-1), m_step(num_steps==1 ? Scalar() : (high-low)/Scalar(num_steps-1)), m_interPacket(plset<Packet>(0))
m_low(low), m_high(high), m_size1(num_steps==1 ? 1 : num_steps-1), m_step(num_steps==1 ? Scalar() : (high-low)/Scalar(num_steps-1)),
m_interPacket(plset<Packet>(0)),
m_flip(std::abs(high)<std::abs(low))
{}
template<typename IndexType>
EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE const Scalar operator() (IndexType i) const {
return (i==m_size1)? m_high : (m_low + i*m_step);
if(m_flip)
return (i==0)? m_low : (m_high - (m_size1-i)*m_step);
else
return (i==m_size1)? m_high : (m_low + i*m_step);
}
template<typename IndexType>
@@ -56,11 +61,22 @@ struct linspaced_op_impl<Scalar,Packet,/*IsInteger*/false>
{
// Principle:
// [low, ..., low] + ( [step, ..., step] * ( [i, ..., i] + [0, ..., size] ) )
Packet pi = padd(pset1<Packet>(Scalar(i)),m_interPacket);
Packet res = padd(pset1<Packet>(m_low), pmul(pset1<Packet>(m_step), pi));
if(i==m_size1-unpacket_traits<Packet>::size+1)
res = pinsertlast(res, m_high);
return res;
if(m_flip)
{
Packet pi = padd(pset1<Packet>(Scalar(i-m_size1)),m_interPacket);
Packet res = padd(pset1<Packet>(m_high), pmul(pset1<Packet>(m_step), pi));
if(i==0)
res = pinsertfirst(res, m_low);
return res;
}
else
{
Packet pi = padd(pset1<Packet>(Scalar(i)),m_interPacket);
Packet res = padd(pset1<Packet>(m_low), pmul(pset1<Packet>(m_step), pi));
if(i==m_size1-unpacket_traits<Packet>::size+1)
res = pinsertlast(res, m_high);
return res;
}
}
const Scalar m_low;
@@ -68,6 +84,7 @@ struct linspaced_op_impl<Scalar,Packet,/*IsInteger*/false>
const Index m_size1;
const Scalar m_step;
const Packet m_interPacket;
const bool m_flip;
};
template <typename Scalar, typename Packet>