| Re: [eigen] How to get triangular lower part of a matrix with dev branche ? |
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Of course :
#include <QR.h>
using namespace Eigen;
typedef Matrix<double,4,4> MAT;
typedef Matrix<double,4,1> VECT;
template<typename MatrixType>
MatrixType triangfactor(MatrixType& V,
Matrix<typename MatrixType::Scalar,MatrixType::RowsAtCompileTime,1>&
coeffs)
{
typedef typename MatrixType::Scalar Scalar;
const int k=coeffs.size();
ei_assert(V.cols()==k && V.rows()>=k && "Vector storing Matrix must
have same columns than coeffs size and more rows than columns");
MatrixType ret=MatrixType::Zero(k,k);
const int j=k;
for(int i=0;i<k;i++)
{
Scalar Vii=V(i,i);
V(i,i)=1;
ret.block(0,i,i,1) = - coeffs(i,0) * V.block(i,0,j-i,i).transpose()
* V.block(i,i,j-i,1);
V(i,i)=Vii;
ret.block(0,i,i,1)=ret.block(0,0,i,i)*ret.block(0,i,i,1);
ret(i,i)=coeffs(i,0);
}
return ret;
}
int main()
{
MAT mat=MAT::Random();
VECT vect=VECT::Random();
MAT tst=triangfactor(MAT(mat.triangularView<Lower>()),vect);
cout<<tst<<endl<<endl;
return 0;
}
On Thu, 20 May 2010 07:16:26 -0400, Benoit Jacob
<jacob.benoit.1@xxxxxxxxx>
wrote:
> 2010/5/20 <vincent.lejeune@xxxxxxxxxx>:
>>
>> Hi,
>>
>>
>>
>> I'm trying to get the lower triangular part of a (non-square) matrix,
but
>>
>> it seems that the part() function is deprecated in Eigen 2.91.
>>
>> Using mat.triangularView<Lower>(), I meet the following compile error :
>
> Sounds like a bug. Can you send us a test program reproducing it?
>
> Benoit
>
>
>>
>>
>>
>> error: invalid initialization of non-const reference of type
>>
>> ‘Eigen::TriangularView<Eigen::Matrix<double, 4, 4, 0, 4, 4>, 1u>&’ from
>> a
>>
>> temporary of type ‘Eigen::TriangularView<Eigen::Matrix<double, 4, 4, 0,
>> 4,
>>
>> 4>, 1u>’
>>
>>
>>
>> That I do not really understand...
>>
>>
>>
>> Thx
>>
>>
>>