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Add lastN shorcuts to seq/seqN.

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This commit is contained in:
Gael Guennebaud 2018-07-23 16:20:25 +02:00
parent 2bf864f1eb
commit c747cde69a
2 changed files with 40 additions and 2 deletions
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34
Eigen/src/Core/ArithmeticSequence.h
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@ -225,7 +225,8 @@ auto seq(FirstType f, LastType l, IncrType incr)
-typename internal::cleanup_index_type<FirstType>::type(f)+CleanedIncrType(incr)) / CleanedIncrType(incr),
CleanedIncrType(incr));
}
#else
#else // EIGEN_HAS_CXX11
template<typename FirstType,typename LastType>
typename internal::enable_if<!(Symbolic::is_symbolic<FirstType>::value || Symbolic::is_symbolic<LastType>::value),
@ -314,10 +315,39 @@ seq(const Symbolic::BaseExpr<FirstTypeDerived> &f, const Symbolic::BaseExpr<Last
typedef typename internal::cleanup_seq_incr<IncrType>::type CleanedIncrType;
return seqN(f.derived(),(l.derived()-f.derived()+CleanedIncrType(incr))/CleanedIncrType(incr), incr);
}
#endif
#endif // EIGEN_HAS_CXX11
#endif // EIGEN_PARSED_BY_DOXYGEN
#if EIGEN_HAS_CXX11
/** \cpp11
* \returns a symbolic ArithmeticSequence representing the last \a size elements with increment \a incr.
*
* It is a shortcut for: \code seqN(last-(size-fix<1>)*incr, size, incr) \endcode
*
* \sa lastN(SizeType), seqN(FirstType,SizeType), seq(FirstType,LastType,IncrType) */
template<typename SizeType,typename IncrType>
auto lastN(SizeType size, IncrType incr)
-> decltype(seqN(Eigen::placeholders::last-(size-fix<1>())*incr, size, incr))
{
return seqN(Eigen::placeholders::last-(size-fix<1>())*incr, size, incr);
}
/** \cpp11
* \returns a symbolic ArithmeticSequence representing the last \a size elements with a unit increment.
*
* It is a shortcut for: \code seq(last+fix<1>-size, last) \endcode
*
* \sa lastN(SizeType,IncrType, seqN(FirstType,SizeType), seq(FirstType,LastType) */
template<typename SizeType>
auto lastN(SizeType size)
-> decltype(seqN(Eigen::placeholders::last+fix<1>()-size, size))
{
return seqN(Eigen::placeholders::last+fix<1>()-size, size);
}
#endif
namespace internal {
// Convert a symbolic span into a usable one (i.e., remove last/end "keywords")

8
test/indexed_view.cpp
View File

@ -293,6 +293,14 @@ void check_indexed_view()
}
#if EIGEN_HAS_CXX11
// check lastN
VERIFY_IS_APPROX( a(lastN(3)), a.tail(3) );
VERIFY( MATCH( a(lastN(3)), "7\n8\n9" ) );
VERIFY_IS_APPROX( a(lastN(fix<3>())), a.tail<3>() );
VERIFY( MATCH( a(lastN(3,2)), "5\n7\n9" ) );
VERIFY( MATCH( a(lastN(3,fix<2>())), "5\n7\n9" ) );
VERIFY( a(lastN(fix<3>())).SizeAtCompileTime == 3 );
VERIFY( (A(all, std::array<int,4>{{1,3,2,4}})).ColsAtCompileTime == 4);
VERIFY_IS_APPROX( (A(std::array<int,3>{{1,3,5}}, std::array<int,4>{{9,6,3,0}})), A(seqN(1,3,2), seqN(9,4,-3)) );