coxeter/trunk/coxeter-sage.patch

   1 See https://github.com/tscrim/coxeter/pull/14
   2
   3 commit 7b46d5ea88cfdcaa4af549f61c58c330fb513948
   4 Author: Jeroen Demeyer <jdemeyer@cage.ugent.be>
   5 Date:   Mon Feb 26 14:43:08 2018 +0100
   6
   7     Add Sage interface
   8
   9 diff --git a/sage.cpp b/sage.cpp
  10 new file mode 100644
  11 index 0000000..74f86be
  12 --- /dev/null
  13 +++ b/sage.cpp
  14 @@ -0,0 +1,56 @@
  15 +/*
  16 +  Coxeter version 3.0 Copyright (C) 2009 Mike Hansen
  17 +  See file main.cpp for full copyright notice
  18 +*/
  19 +
  20 +#include "sage.h"
  21 +
  22 +namespace sage {
  23 +
  24 +  void interval(List<CoxWord>& list, CoxGroup& W, const CoxWord& g, const CoxWord& h)
  25 +
  26 +  /*
  27 +     Returns a list of the elements in the Bruhat interval between g and h.
  28 +     Note that this assumes that g and h are in order.
  29 +   */
  30 +  {
  31 +    if (not W.inOrder(g,h)) {
  32 +      return;
  33 +    }
  34 +
  35 +    W.extendContext(h);
  36 +
  37 +    CoxNbr x = W.contextNumber(g);
  38 +    CoxNbr y = W.contextNumber(h);
  39 +
  40 +    BitMap b(W.contextSize());
  41 +    W.extractClosure(b,y);
  42 +
  43 +    BitMap::ReverseIterator b_rend = b.rend();
  44 +    List<CoxNbr> res(0);
  45 +
  46 +    for (BitMap::ReverseIterator i = b.rbegin(); i != b_rend; ++i)
  47 +      if (not W.inOrder(x,*i)) {
  48 +        BitMap bi(W.contextSize());
  49 +        W.extractClosure(bi,*i);
  50 +        CoxNbr z = *i; // andnot will invalidate iterator
  51 +        b.andnot(bi);
  52 +        b.setBit(z);   // otherwise the decrement will not be correct
  53 +      } else
  54 +        res.append(*i);
  55 +
  56 +    schubert::NFCompare nfc(W.schubert(),W.ordering());
  57 +    Permutation a(res.size());
  58 +    sortI(res,nfc,a);
  59 +
  60 +    list.setSize(0);
  61 +    for (size_t j = 0; j < res.size(); ++j) {
  62 +      CoxWord w(0);
  63 +      W.schubert().append(w, res[a[j]]);
  64 +      list.append(w);
  65 +    }
  66 +
  67 +    return;
  68 +  }
  69 +
  70 +}
  71 diff --git a/sage.h b/sage.h
  72 new file mode 100644
  73 index 0000000..5b3df8a
  74 --- /dev/null
  75 +++ b/sage.h
  76 @@ -0,0 +1,23 @@
  77 +/*
  78 +  Coxeter version 3.0 Copyright (C) 2009 Mike Hansen
  79 +  See file main.cpp for full copyright notice
  80 +*/
  81 +
  82 +#ifndef SAGE_H /* guard against multiple inclusions */
  83 +#define SAGE_H
  84 +
  85 +#include "globals.h"
  86 +#include "coxgroup.h"
  87 +#include "coxtypes.h"
  88 +#include "schubert.h"
  89 +#include "list.h"
  90 +
  91 +namespace sage {
  92 +  using namespace coxeter;
  93 +  using namespace coxtypes;
  94 +  using namespace list;
  95 +
  96 +  void interval(List<CoxWord>& result, CoxGroup& W, const CoxWord& g, const CoxWord& h);
  97 +}
  98 +
  99 +#endif