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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Casting matrices
- From: "Timothy Hunter" <tjhunter@xxxxxxxxxxxx>
- Date: Sun, 9 Nov 2008 16:19:03 -0800
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I should read the documentation more carefully....
Maybe this feature should be added in the tutorial
(http://eigen.tuxfamily.org/api/TutorialCore.html) ?
On Sun, Nov 9, 2008 at 4:08 PM, Benoît Jacob <jacob@xxxxxxxxxxxxxxx> wrote:
> On Monday 10 November 2008 00:45:12 Timothy Hunter wrote:
>> Hello list,
>> I want to convert a Eigen::MatrixXi to a double * (already allocated
>> and of the right size).
>> A way to do it is to iterate:
>> for(int i=0;i<mat.rows();++i)
>> for(int j=0;j<mat.cols();++j)
>> double_ptr[i*mat.cols()+j] = static_cast<double>(mat(i,j));
>>
>> However I would like to use MatrixXd::Map in this occasion.
>
> Then all you need to do is:
>
> MatrixXf::Map(double_ptr, mat.rows(), mat.cols())
> = mat.cast<double>();
>
> Note that the Matrix::Map static method has been added in SVN very recently,
> beta1 is not enough. (The old way of constructing a Map<MatrixXf> explicitly
> is less practical here, cf. the thread on this list with Cristovao).
>
>>
>> More generally, it is not currently possible to do casting operations
>> like Vector3i = Vector3d and I want to add it on the wishlist if you
>> know of an elegant way to do it.
>
> It is already possible, you can do:
>
> Vector3d vd;
> Vector3i vi = vd.cast<int>();
>
> Cheers,
> Benoit
>
> ---
>
>