outer product of two vectors

[Nikki Holtzer]

Hello everyone,

I am trying to form a cross product/ outer product of two vectors of type deallii:Vector<double>. I have attempted to use some of the built in functions for the outer product from the Tensor Class but have had no luck. I can't seem to get anything other than

error: no matching function for call to 'outer_product(vec1, vec2);'

I have tried recasting my vec1/vec2 as Tensors but have run into a similar error message. 

Is there a built in vector cross product? Alternatively, how could I recast my vectors and then use the built in functions from the Tensor Class and finally recast them back into vectors? 

Thank you!

[Wolfgang Bangerth]

The easy way is to do

const unsigned int n = vec.size();
FullMatrix<double> o_p (n,n);
for (unsigned int i=0; i<n; ++i)
for (unsigned int j=0; j<n; ++j)
o_p(i,j) = vec[i] * vec[j];

But the issue is that generally you end up with a full matrix this way. Is
that what you want? How large are your vectors?

Best
W.

--
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Wolfgang Bangerth email: bang...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/

[Marc Fehling]

Please have a look at this particular test which showcases how an outer product can be achieved with deal.II!

https://github.com/dealii/dealii/blob/master/tests/full_matrix/full_matrix_57.cc

Hope this helps!

Marc

[Nikki Holtzer]

Thank you!