Re: [eigen] Forcing a conversion to ColMajor

[Douglas Bates <bates@xxxxxxxxxxxxx>]

On Mon, Jul 30, 2012 at 3:00 AM, Gael Guennebaud
<gael.guennebaud@xxxxxxxxx> wrote:
> hi,
>
> I think you can simply drop the explicit ColMajor:
>
> typename Eigen::internal::conditional<T::IsRowMajor,
>   Eigen::Matrix<typename T::Scalar,
>   T::RowsAtCompileTime,T::ColsAtCompileTime>,
>   const T&>::type objCopy(obj);

That works, thanks.

> On Sat, Jul 28, 2012 at 8:12 PM, Douglas Bates <bates@xxxxxxxxxxxxx> wrote:
>> On Sat, Jul 28, 2012 at 12:40 PM, Douglas Bates <bates@xxxxxxxxxxxxx> wrote:
>>> On Sat, Jul 28, 2012 at 12:11 PM, Douglas Bates <bates@xxxxxxxxxxxxx> wrote:
>>>> On Sat, Jul 28, 2012 at 2:52 AM, Gael Guennebaud
>>>> <gael.guennebaud@xxxxxxxxx> wrote:
>>>>> Hi,
>>>>>
>>>>> you could do something like:
>>>>>
>>>>> typename Eigen::internal::conditional<T::IsRowMajor,
>>>>>   Eigen::Matrix<typename T::Scalar,
>>>>> T::RowsAtCompileTime,T::ColsAtCompileTime,ColMajor>,
>>>>>   const T&>::type objCopy(obj);
>>>>>
>>>>> and then use objCopy instead. If T is column major, then objCopy will
>>>>> just be an alias (const ref).
>>>>
>>>> Thanks for the suggestion.  That version fails with an
>>>> INVALID_MATRIX_TEMPLATE_PARAMETERS error when trying to do the objCopy
>>>> on a row-major object.
>>>>
>>>> ./include/Eigen/src/Core/Matrix.h:280:13: note: in instantiation of
>>>> member function
>>>> 'Eigen::PlainObjectBase<Eigen::Matrix<std::complex<double>, 1, -1, 0,
>>>> 1, -1> >::_check_template_params' requested here
>>>>       Base::_check_template_params();
>>>>             ^
>>>> ./include/RcppEigenWrap.h:89:31: note: in instantiation of function
>>>> template specialization 'Eigen::Matrix<std::complex<double>, 1, -1, 0,
>>>> 1, -1>::Matrix<Eigen::Matrix<std::complex<double>, 1, -1, 1, 1, -1> >'
>>>> requested here
>>>>               const T&>::type objCopy(obj);
>>>>
>>>> I think this is triggered by an object of the form
>>>>
>>>> Eigen::RowVectorXcd::Zero(5)
>>>>
>>>> and my guess is that the condition failing is
>>>>
>>>> EIGEN_IMPLIES(MaxRowsAtCompileTime==1 && MaxColsAtCompileTime!=1,
>>>> (Options&RowMajor)==RowMajor)
>>>
>>> Probably I should just trap the case of MaxRowsAtCompileTime == 1
>>> because there really is no difference between row-major and
>>> column-major in terms of the object returned to R.
>>
>> The last part of that sentence was for the case of
>> MaxRowsAtCompileTime == 1.  Of course I have since found out that I
>> need to catch that case at compile time, not run time, for which I
>> will need to do more template metaprogramming than I have done in the
>> past.
>>
>>
>
>