Grid/TODO

* FIXME audit
* Replace vset with a call to merge.; 
* care in Gmerge,Gextract over set.
* Const audit
* extract / merge extra implementation removal      


* Conditional execution, where etc...                -----DONE, simple test
* Integer relational support                         -----DONE
* Coordinate information, integers etc...            -----DONE
* Integer type padding/union to vector.              -----DONE 
* LatticeCoordinate[mu]                              -----DONE


* Stencil operator support                           -----Initial thoughts

* Subset support, slice sums etc...                  -----Only need slice sum?
                                                     -----Generic cartesian subslicing?
                                                     -----Array ranges / boost extents?
                                                     -----Multigrid grid transferral.
                                                     -----Suggests generalised cartesian subblocking
                                                          sums, returning modified grid.

i)  Two classes of subset;   red black parity subsetting (pick checkerboard).
                             cartesian sub-block subsetting


ii) Need to be able to project one Grid to another Grid.

Interface: (?)

Lattice<vobj> coarse_data SubBlockSum (GridBase *CoarseGrid, Lattice<vobj> &fine_data)

Operation ensure either:
 rd[dim] divide rd[dim] fine_data

This will give a distributed array over mpi ranks in a given dim IF coarse gd != 1 and _processors[d]>1
Dimension can be *replicated* on all ranks in dimension. Need a "replicated" option on GridCartesian etc..

This will give "slice" summation and fourier projection assistance.

    Generic concept is to subdivide (based on RD so applies to red/black or full).
    Return a type on SUB-grid from CellSum TOP-grid
    SUB-grid need not distribute but be replicated in some dims if that is how the
    cartesian communicator works.

Instead of subsetting 

iii) No general permutation map.

* Consider switch std::vector to boost arrays.
  boost::multi_array<type, 3> A()...    to replace multi1d, multi2d etc..

*? Cell definition <-> sliceSum.
 ? Replicated arrays.

* Check for missing functionality                    - partially audited against QDP++ layout

* Optimise the extract/merge SIMD routines; Azusa??

 - I have collated into single location at least.
 - Need to use _mm_*insert/extract routines.

* Conformable test in Cshift routines.

* Gamma/Dirac structures

* Fourspin, two spin project

* Broadcast, reduction tests. innerProduct, localInnerProduct

* QDP++ regression suite and comparative benchmark

* NERSC Lattice loading, plaquette test


* I/O support
  - MPI IO?
  - BinaryWriter, TextWriter etc...
  - protocol buffers?
  - 
// Cartesian grid inheritance
//            Grid::GridBase
//                     |
//           __________|___________
//          |                      |
// Grid::GridCartesian   Grid::GridCartesianRedBlack
//
// TODO: document the following as an API guaranteed public interface

    /* 
     *       Rough map of functionality against QDP++ Layout
     *
     *       Param     |     Grid                     |     QDP++             
     *       -----------------------------------------
     *                 |                              |
     *        void     |     oSites, iSites, lSites   |  sitesOnNode 
     *        void     |     gSites                   |  vol
     *                 |                              |
     *        gcoor    |     oIndex, iIndex           |  linearSiteIndex // no virtual node in QDP
     *        lcoor    |                              |
     * 
     *        void     |     CheckerBoarded           |  -        // No checkerboarded in QDP
     *        void     |     FullDimensions           |  lattSize
     *        void     |     GlobalDimensions         |  lattSize // No checkerboarded in QDP
     *        void     |     LocalDimensions          |  subgridLattSize
     *        void     |     VirtualLocalDimensions   |  subgridLattSize // no virtual node in QDP
     *                 |                              |
     *       int x 3   |     oiSiteRankToGlobal       |  siteCoords
     *                 |     ProcessorCoorLocalCoorToGlobalCoor | 
     *                 |                              |
     *     vector<int> |     GlobalCoorToRankIndex   |  nodeNumber(coord)
     *     vector<int> |     GlobalCoorToProcessorCoorLocalCoor|  nodeCoord(coord)
     *                 |                              |
     *     void        |     Processors               |  logicalSize    // returns cart array shape
     *     void        |     ThisRank        |  nodeNumber();  // returns this node rank
     *     void        |     ThisProcessorCoor        |    // returns this node coor
     *     void        |     isBoss(void)             |  primaryNode();
     *                 |                              |
     *                 |     RankFromProcessorCoor    |  getLogicalCoorFrom(node)
     *                 |     ProcessorCoorFromRank    |  getNodeNumberFrom(logical_coord)
     */
  // Work out whether to permute 
  // ABCDEFGH ->   AE BF CG DH       permute              wrap num
  //
  // Shift 0       AE BF CG DH       0 0 0 0    ABCDEFGH   0   0
  // Shift 1       BF CG DH AE       0 0 0 1    BCDEFGHA   0   1
  // Shift 2       CG DH AE BF       0 0 1 1    CDEFGHAB   0   2
  // Shift 3       DH AE BF CG       0 1 1 1    DEFGHABC   0   3
  // Shift 4       AE BF CG DH       1 1 1 1    EFGHABCD   1   0 
  // Shift 5       BF CG DH AE       1 1 1 0    FGHACBDE   1   1 
  // Shift 6       CG DH AE BF       1 1 0 0    GHABCDEF   1   2
  // Shift 7       DH AE BF CG       1 0 0 0    HABCDEFG   1   3

  // Suppose 4way simd in one dim.
  // ABCDEFGH ->   AECG BFDH      permute              wrap num

  // Shift 0       AECG BFDH      0,00 0,00 ABCDEFGH         0     0
  // Shift 1       BFDH CGEA      0,00 1,01 BCDEFGHA         0     1
  // Shift 2       CGEA DHFB      1,01 1,01 CDEFGHAB         1     0
  // Shift 3       DHFB EAGC      1,01 1,11 DEFGHABC         1     1
  // Shift 4       EAGC FBHD      1,11 1,11 EFGHABCD         2     0 
  // Shift 5       FBHD GCAE      1,11 1,10 FGHABCDE         2     1
  // Shift 6       GCAE HDBF      1,10 1,10 GHABCDEF         3     0
  // Shift 7       HDBF AECG      1,10 0,00 HABCDEFG         3     1

  // Generalisation to 8 way simd, 16 way simd required.
  //
  // Need log2 Nway masks. consisting of 
  //	    1 bit  256 bit granule
  //	    2 bit  128 bit granule
  //        4 bits 64  bit granule
  //        8 bits 32  bit granules
  //
  //        15 bits....
    // TODO
    //
    // Base class to share common code between vRealF, VComplexF etc...
    //
    // lattice Broad cast assignment
    //
    // where() support
    // implement with masks, and/or? Type of the mask & boolean support?
    //
    // Unary functions
    // cos,sin, tan, acos, asin, cosh, acosh, tanh, sinh, // Scalar<vReal> only arg
    // exp, log, sqrt, fabs
    //
    // transposeColor, transposeSpin,
    // adjColor, adjSpin,
    // traceColor, traceSpin.
    // peekColor, peekSpin + pokeColor PokeSpin
    //
    // copyMask.
    //
    // localMaxAbs
    //
    // norm2,
    // sumMulti equivalent.
    // Fourier transform equivalent.
    //