<div dir="ltr"><div><div><div><div>Hello Cyril,<br><br></div>The solution I provided works indeed only if you have an itk::Matrix and an itk::Vector, compute the product, and then convert it to variable size containers.<br></div>It seems that what you want to do is the reverse.<br></div>One solution is to work directly with vnl_vector and vnl_matrix:<br></div>//Input data<br><div>itk::VariableLengthVector<float> v_vec;<br>itk::VariableSizeMatrix<float> v_mat;<br>v_vec.SetSize(3);<br>v_vec.Fill(1.7);<br>v_mat.Fill(1.3);<br></div><div>// Converting data to vnl vector and matrix<br></div><div>vnl_vector<float> vnl_vec(v_vec.GetDataPointer(),v_vec.GetSize());<br>vnl_matrix<float> vnl_mat=v_mat.GetVnlMatrix();<br>vnl_vector<float> vnl_vec_res=vnl_mat*vnl_vec;<br></div><div>// Converting result back<br></div><div>v_vec.SetData(vnl_vec_res.data_block(),3,false);<br><br></div><div>You could also work with itk::Vector and itk::Matrix if you know the size is within a certain range (i.e. dimensions 2 and 3). You could use<br></div><div>templates over this range.<br></div><div><br></div><div>Hope this helps<br></div><div>Francois<br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Sep 19, 2016 at 4:02 PM, Cyril Mory <span dir="ltr"><<a href="mailto:cyril.mory@creatis.insa-lyon.fr" target="_blank">cyril.mory@creatis.insa-lyon.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<p>Thanks for this reply, but part of it is not what I was looking
for. In my understanding, the solution you suggested allows to
multiply a VariableSizeMatrix with a Vector, and then store the
result into a VariableLenghtVector. But my input is also a
VariableLengthVector, not a Vector. <br>
</p>
<p>So let me be clearer: I want to multiply a VariableSizeMatrix
with a VariableLengthVector. Is there a way to extract from this
VariableLengthVector something that can be multiplied with
VariableSizeMatrix.<wbr>GetVnlMatrix() ? Maybe I should copy my
VariableLengthVector into a vnl_vector ?</p>
<p>I do not know the size of that VariableLengthVector at compile
time, so I cannot create an itk::Vector of the correct size.<br>
</p>
Best,<br>
Cyril<div><div class="h5"><br>
<br>
<div>On 09/19/2016 06:12 PM, Francois Budin
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<div>
<div>
<div>
<div>
<div>
<div>
<div>
<div>Hello Cyril,<br>
<br>
</div>
For the matrix conversion, you can use
itk::Matrix::GetVnlMatrix() to extract the
matrix from the itk::Matrix object, and use
assign that vnl matrix to your
itk::VariableLengthVector using operator=(const
vnl_matrix< T > &matrix).<br>
<br>
</div>
</div>
itk::Matrix<float,3,3> mat;<br>
</div>
itk::VariableSizeMatrix<float> v_mat;<br>
</div>
v_mat = mat.GetVnlMatrix();<br>
<br>
</div>
For the vectors, you could get access to the data from
itk::Vector and pass the pointer to the data to your
itk::VariableLengthVector.<br>
</div>
itk::Vector<float> vec;<br>
itk::VariableLengthVector<<wbr>float> v_vec;<br>
v_vec.SetSize(3);<br>
v_vec.SetData(vec.<wbr>GetDataPointer(),false);<br>
</div>
</div>
<div>
<div>
<div>
<div>
<div>
<div><br>
<div>
<div>Be careful with the memory management for the
vector as the data is still managed by the
itk::Vector in this example, so the data will be
destroyed if the vector is destroyed (if you go
out of scope).<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Sep 19, 2016 at 11:05 AM, Cyril
Mory <span dir="ltr"><<a href="mailto:cyril.mory@creatis.insa-lyon.fr" target="_blank">cyril.mory@creatis.insa-lyon.<wbr>fr</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi ITK
users,<br>
<br>
I have some working ITK code with itk::Matrix by itk::Vector
multiplications, and I need to change to
itk::VariableSizeMatrix and itk::VariableLengthVector.<br>
<br>
Simply writing<br>
<br>
"myResultVector = myMatrix * myInputVector"<br>
<br>
works with itk::Matrix and itk::Vector objects, but not with
their VariableSize/Length counterparts. Is there a way to do
it, other than writing the matrix by vector multiplication
for-loops myself ?<br>
<br>
Regards,<br>
<br>
Cyril<br>
<br>
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