[Insight-users] Norm in ITK

[Luis Ibanez]

Hi Lisa,


The only embarrassing questions
are those that are left unasked        :-)


At this point we don't really have an ITK
class that encompasses the concept of
an "Array of Vectors", although you can
construct it with existing classes.

May I presume that the norm that you want
to compute for the Array of Vector is the
Sum of norms of all the Vectors in the array ?

If so, at this point the easy way to do this
would be to Instantiate an Array of Vectors,

and do a for loop visiting all the elements...

As Array classes you could use the:

typedef itk::Vectors< float, N >   VectorType;

...

itk::Array< VectorType >

or

itk::VectorContainer<  VectorType >

or simply one of the STL containers

std::list< VectorType >
std::vector< VectorType >

The code could look like:

typedef std::vector< VectorType >  ArrayOfVectorType;

ArrayOfVectorType   array = this->GetArraySomehow();

ArrayOfVectorType::const_iterator  itr = array.begin();

double sum = 0.0;
while( itr != array.end() )
  {
  sum += itr->GetNorm();
  ++itr;
  }

std::cout << sum << std::endl;

http://www.itk.org/Doxygen/html/classitk_1_1Vector.html#a0f103636ffc85fd3df1ae6c838d3e70e



Depending on your definition of norm
for an array of vectors, the code above
may need some retouching.


   HTH


       Luis


------------------------------------------------------
On Tue, May 22, 2012 at 2:06 AM, Lisa Dean <lisadean.leo at gmail.com> wrote:

>
>
> Hi Users,
>
>
> Forgive the embarrassingly basic question, but how do I find the squared
> norm of an itk array of vectors?
>
>
>
> Thanks for the help
>
> Lisa
>
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