[Dune-devel] Destiny of MultiIndex
Dominic Kempf
dominic.r.kempf at gmail.com
Thu Mar 19 17:32:08 CET 2015
Does it make sense to tackle this before 2.4? I would like to finish the
TensorGridFactory before the release. If we postpone the MultiIndex in
dune-common, I will go ahead with the factory.
Dominic
On Tue, Mar 17, 2015 at 4:45 PM, Oliver Sander <sander at igpm.rwth-aachen.de>
wrote:
> Hi Martin,
> interesting how different people view this as different things.
>
> > personally, I never understood the class MultiIndex in the
> StructuredGridFactory. To me, a multiindex is an array of integers with
> "vector space operations" (have a look at the MultiIndex in
> > dune-spgrid, if you like). Unlike in StructuredGridFactory, it is not an
> iterator of any kind, i.e., ++multiIndex does not make sense to me.
>
> I have always looked at multi-indices as dyadic representations of numbers,
> where the base of each digit can be chosen separately. Then, ++multiIndex
> makes perfect sense -- you simply increment the numbers.
>
> >
> > What you are looking for (as far as I underdand it) is a special kind of
> a set of multiindices: Those within within a "cube". This could be realized
> as an iterator range of multiindices. But for
> > multiindices, other ranges are of interest too (e.g., all multiindices
> within a "simplex").
>
> I've never thought about the simplex problem; you are right that this can
> be of interest, too.
> Without having giving it much thought I tend to think that your approach
> (i.e., having algorithmically
> defined sets of multi-indices, and iterators over these sets) is more
> general, and hence preferable.
>
> Is your implementation easy to look at and understand?
>
> Cheers,
> Oliver
>
>
> >
> > Apart from such implementation details, I'd be very happy to have such a
> concept in dune-common, as it would reduce the SPGrid code by a few hundred
> (basically redundant) lines of code.
> >
> > Best,
> >
> > Martin
> >
> >
> > On 03/16/2015 10:26 PM, Oliver Sander wrote:
> >> Am 16.03.2015 um 19:33 schrieb Dominic Kempf:
> >>> Sounds like a good idea to me. Maybe we could/should extend the
> interface
> >>> then? postfix operator++, the operator--s, logical and stream operators
> >>> come to my mind.
> >>
> >> Definitely. Also, one usually needs a way to iterate over the entire
> range
> >> of the multi-index. Previously I have used a method 'cycle', which
> says how
> >> many times I can call operator++ before I getting an overflow, but
> there may
> >> be better solutions.
> >>
> >>>
> >>> On Mon, Mar 16, 2015 at 7:17 PM, Oliver Sander <
> sander at igpm.rwth-aachen.de>
> >>> wrote:
> >>>
> >>>> Hi all,
> >>>>
> >>>>>
> >>>>> Move MultiIndex class from StructuredGridFactory to a separate
> header
> >>>>>
> >>>>> The TensorGridFactory needs the same class, so I move it to a
> new
> >>>> header.
> >>>>
> >>>> a smart move. I have needed (and reimplemented) such a class again
> and
> >>>> again.
> >>>> Maybe we should move multiindex.hh into dune-common right away?
> >>>> --
> >>>> Oliver
> >>>>
> >>>>
> >>>>>
> >>>>> dune/grid/utility/CMakeLists.txt | 1 +
> >>>>> dune/grid/utility/Makefile.am | 1 +
> >>>>> dune/grid/utility/multiindex.hh | 57
> >>>> ++++++++++++++++++++++++++++++
> >>>>> dune/grid/utility/structuredgridfactory.hh | 53
> >>>> +++------------------------
> >>>>> dune/grid/utility/tensorgridfactory.hh | 2 ++
> >>>>> 5 files changed, 65 insertions(+), 49 deletions(-)
> >>>>> create mode 100644 dune/grid/utility/multiindex.hh
> >>>>>
> >>>>>
> >>>>>
> >>>>> diff --git a/dune/grid/utility/CMakeLists.txt
> >>>> b/dune/grid/utility/CMakeLists.txt
> >>>>> index 1c42604..15d2311 100644
> >>>>> --- a/dune/grid/utility/CMakeLists.txt
> >>>>> +++ b/dune/grid/utility/CMakeLists.txt
> >>>>> @@ -8,6 +8,7 @@ set(HEADERS
> >>>>> gridtype.hh
> >>>>> hierarchicsearch.hh
> >>>>> hostgridaccess.hh
> >>>>> + multiindex.hh
> >>>>> parmetisgridpartitioner.hh
> >>>>> persistentcontainer.hh
> >>>>> persistentcontainerinterface.hh
> >>>>> diff --git a/dune/grid/utility/Makefile.am
> >>>> b/dune/grid/utility/Makefile.am
> >>>>> index e14c152..d81c3e2 100644
> >>>>> --- a/dune/grid/utility/Makefile.am
> >>>>> +++ b/dune/grid/utility/Makefile.am
> >>>>> @@ -10,6 +10,7 @@ gridutility_HEADERS =
> \
> >>>>> gridtype.hh \
> >>>>> hierarchicsearch.hh \
> >>>>> hostgridaccess.hh \
> >>>>> + multiindex.hh \
> >>>>> parmetisgridpartitioner.hh \
> >>>>> persistentcontainer.hh \
> >>>>> persistentcontainerinterface.hh \
> >>>>> diff --git a/dune/grid/utility/multiindex.hh
> >>>> b/dune/grid/utility/multiindex.hh
> >>>>> new file mode 100644
> >>>>> index 0000000..b6b281f
> >>>>> --- /dev/null
> >>>>> +++ b/dune/grid/utility/multiindex.hh
> >>>>> @@ -0,0 +1,57 @@
> >>>>> +#ifndef DUNE_GRID_UTILITY_MULTIINDEX_HH
> >>>>> +#define DUNE_GRID_UTILITY_MULTIINDEX_HH
> >>>>> +
> >>>>> +/** \file
> >>>>> + * \brief Implements a multiindex with arbitrary dimension and
> fixed
> >>>> index ranges
> >>>>> + * This is used by various factory classes.
> >>>>> + */
> >>>>> +
> >>>>> +#include<array>
> >>>>> +
> >>>>> +namespace Dune
> >>>>> +{
> >>>>> + namespace FactoryUtilities
> >>>>> + {
> >>>>> + template<std::size_t dim>
> >>>>> + class MultiIndex : public std::array<unsigned int,dim>
> >>>>> + {
> >>>>> + // The range of each component
> >>>>> + std::array<unsigned int,dim> limits_;
> >>>>> +
> >>>>> + public:
> >>>>> + /** \brief Constructor with a given range for each digit */
> >>>>> + MultiIndex(const std::array<unsigned int,dim>& limits) :
> >>>> limits_(limits)
> >>>>> + {
> >>>>> + std::fill(this->begin(), this->end(), 0);
> >>>>> + }
> >>>>> +
> >>>>> + /** \brief Increment the MultiIndex */
> >>>>> + MultiIndex<dim>& operator++()
> >>>>> + {
> >>>>> + for (int i=0; i<dim; i++)
> >>>>> + {
> >>>>> + // Augment digit
> >>>>> + (*this)[i]++;
> >>>>> +
> >>>>> + // If there is no carry-over we can stop here
> >>>>> + if ((*this)[i]<limits_[i])
> >>>>> + break;
> >>>>> +
> >>>>> + (*this)[i] = 0;
> >>>>> + }
> >>>>> + return *this;
> >>>>> + }
> >>>>> +
> >>>>> + /** \brief Compute how many times you can call operator++ before
> >>>> getting to (0,...,0) again */
> >>>>> + size_t cycle() const
> >>>>> + {
> >>>>> + size_t result = 1;
> >>>>> + for (int i=0; i<dim; i++)
> >>>>> + result *= limits_[i];
> >>>>> + return result;
> >>>>> + }
> >>>>> + };
> >>>>> + }
> >>>>> +}
> >>>>> +
> >>>>> +#endif
> >>>>> diff --git a/dune/grid/utility/structuredgridfactory.hh
> >>>> b/dune/grid/utility/structuredgridfactory.hh
> >>>>> index 8832149..8e2700a 100644
> >>>>> --- a/dune/grid/utility/structuredgridfactory.hh
> >>>>> +++ b/dune/grid/utility/structuredgridfactory.hh
> >>>>> @@ -19,6 +19,7 @@
> >>>>> #include <dune/common/shared_ptr.hh>
> >>>>>
> >>>>> #include <dune/grid/common/gridfactory.hh>
> >>>>> +#include <dune/grid/utility/multiindex.hh>
> >>>>> #include <dune/grid/yaspgrid.hh>
> >>>>>
> >>>>> namespace Dune {
> >>>>> @@ -34,59 +35,13 @@ namespace Dune {
> >>>>>
> >>>>> static const int dimworld = GridType::dimensionworld;
> >>>>>
> >>>>> - /** \brief dim-dimensional multi-index. The range for each
> >>>> component can be set individually
> >>>>> - */
> >>>>> - class MultiIndex
> >>>>> - : public array<unsigned int,dim>
> >>>>> - {
> >>>>> -
> >>>>> - // The range of each component
> >>>>> - array<unsigned int,dim> limits_;
> >>>>> -
> >>>>> - public:
> >>>>> - /** \brief Constructor with a given range for each digit */
> >>>>> - MultiIndex(const array<unsigned int,dim>& limits)
> >>>>> - : limits_(limits)
> >>>>> - {
> >>>>> - std::fill(this->begin(), this->end(), 0);
> >>>>> - }
> >>>>> -
> >>>>> - /** \brief Increment the MultiIndex */
> >>>>> - MultiIndex& operator++() {
> >>>>> -
> >>>>> - for (int i=0; i<dim; i++) {
> >>>>> -
> >>>>> - // Augment digit
> >>>>> - (*this)[i]++;
> >>>>> -
> >>>>> - // If there is no carry-over we can stop here
> >>>>> - if ((*this)[i]<limits_[i])
> >>>>> - break;
> >>>>> -
> >>>>> - (*this)[i] = 0;
> >>>>> -
> >>>>> - }
> >>>>> - return *this;
> >>>>> - }
> >>>>> -
> >>>>> - /** \brief Compute how many times you can call operator++
> before
> >>>> getting to (0,...,0) again */
> >>>>> - size_t cycle() const {
> >>>>> - size_t result = 1;
> >>>>> - for (int i=0; i<dim; i++)
> >>>>> - result *= limits_[i];
> >>>>> - return result;
> >>>>> - }
> >>>>> -
> >>>>> - };
> >>>>> -
> >>>>> /** \brief Insert a structured set of vertices into the
> factory */
> >>>>> static void insertVertices(GridFactory<GridType>& factory,
> >>>>> const FieldVector<ctype,dimworld>&
> >>>> lowerLeft,
> >>>>> const FieldVector<ctype,dimworld>&
> >>>> upperRight,
> >>>>> const array<unsigned int,dim>&
> vertices)
> >>>>> {
> >>>>> -
> >>>>> - MultiIndex index(vertices);
> >>>>> + FactoryUtilities::MultiIndex<dim> index(vertices);
> >>>>>
> >>>>> // Compute the total number of vertices to be created
> >>>>> int numVertices = index.cycle();
> >>>>> @@ -166,7 +121,7 @@ namespace Dune {
> >>>>> cornersTemplate[i] += unitOffsets[j];
> >>>>>
> >>>>> // Insert elements
> >>>>> - MultiIndex index(elements);
> >>>>> + FactoryUtilities::MultiIndex<dim> index(elements);
> >>>>>
> >>>>> // Compute the total number of elementss to be created
> >>>>> int numElements = index.cycle();
> >>>>> @@ -234,7 +189,7 @@ namespace Dune {
> >>>>>
> >>>>> // Loop over all "cubes", and split up each cube into dim!
> >>>>> // (factorial) simplices
> >>>>> - MultiIndex elementsIndex(elements);
> >>>>> + FactoryUtilities::MultiIndex<dim> elementsIndex(elements);
> >>>>> size_t cycle = elementsIndex.cycle();
> >>>>>
> >>>>> for (size_t i=0; i<cycle; ++elementsIndex, i++) {
> >>>>> diff --git a/dune/grid/utility/tensorgridfactory.hh
> >>>> b/dune/grid/utility/tensorgridfactory.hh
> >>>>> index 971bc4e..8aa47cf 100644
> >>>>> --- a/dune/grid/utility/tensorgridfactory.hh
> >>>>> +++ b/dune/grid/utility/tensorgridfactory.hh
> >>>>> @@ -19,6 +19,8 @@
> >>>>> #include<memory>
> >>>>> #include<vector>
> >>>>>
> >>>>> +#include<dune/grid/utility/multiindex.hh>
> >>>>> +
> >>>>> namespace Dune
> >>>>> {
> >>>>> // forward declaration of TensorGridFactoryCreator, which is the
> real
> >>>> factory
> >>>>>
> >>>>> _______________________________________________
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> >>>>>
> >>>>
> >>>>
> >>>>
> >>>> _______________________________________________
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> >>>>
> >>>>
> >>>
> >>
> >>
> >>
> >>
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> >>
> >
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>
>
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