GetFEM++  5.3
gmm_domain_decomp.h
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30 ===========================================================================*/
31 
32 /** @file gmm_domain_decomp.h
33  @author Yves Renard <Yves.Renard@insa-lyon.fr>
34  @date May 21, 2004.
35  @brief Domain decomposition.
36 */
37 #ifndef GMM_DOMAIN_DECOMP_H__
38 #define GMM_DOMAIN_DECOMP_H__
39 
40 #include "gmm_kernel.h"
41 #include <map>
42 
43 
44 namespace gmm {
45 
46  /** This function separates into small boxes of size msize with a ratio
47  * of overlap (in [0,1[) a set of points. The result is given into a
48  * vector of sparse matrices vB.
49  */
50  template <typename Matrix, typename Point>
51  void rudimentary_regular_decomposition(std::vector<Point> pts,
52  double msize,
53  double overlap,
54  std::vector<Matrix> &vB) {
55  typedef typename linalg_traits<Matrix>::value_type value_type;
56  typedef abstract_null_type void_type;
57  typedef std::map<size_type, void_type> map_type;
58 
59  size_type nbpts = pts.size();
60  if (!nbpts || pts[0].size() == 0) { vB.resize(0); return; }
61  int dim = int(pts[0].size());
62 
63  // computation of the global box and the number of sub-domains
64  Point pmin = pts[0], pmax = pts[0];
65  for (size_type i = 1; i < nbpts; ++i)
66  for (int k = 0; k < dim; ++k) {
67  pmin[k] = std::min(pmin[k], pts[i][k]);
68  pmax[k] = std::max(pmax[k], pts[i][k]);
69  }
70 
71  std::vector<size_type> nbsub(dim), mult(dim);
72  std::vector<int> pts1(dim), pts2(dim);
73  size_type nbtotsub = 1;
74  for (int k = 0; k < dim; ++k) {
75  nbsub[k] = size_type((pmax[k] - pmin[k]) / msize)+1;
76  mult[k] = nbtotsub; nbtotsub *= nbsub[k];
77  }
78 
79  std::vector<map_type> subs(nbtotsub);
80  // points ventilation
81  std::vector<size_type> ns(dim), na(dim), nu(dim);
82  for (size_type i = 0; i < nbpts; ++i) {
83  for (int k = 0; k < dim; ++k) {
84  register double a = (pts[i][k] - pmin[k]) / msize;
85  ns[k] = size_type(a) - 1; na[k] = 0;
86  pts1[k] = int(a + overlap); pts2[k] = int(ceil(a-1.0-overlap));
87  }
88  size_type sum = 0;
89  do {
90  bool ok = 1;
91  for (int k = 0; k < dim; ++k)
92  if ((ns[k] >= nbsub[k]) || (pts1[k] < int(ns[k]))
93  || (pts2[k] > int(ns[k]))) { ok = false; break; }
94  if (ok) {
95  size_type ind = ns[0];
96  for (int k=1; k < dim; ++k) ind += ns[k]*mult[k];
97  subs[ind][i] = void_type();
98  }
99  for (int k = 0; k < dim; ++k) {
100  if (na[k] < 2) { na[k]++; ns[k]++; ++sum; break; }
101  na[k] = 0; ns[k] -= 2; sum -= 2;
102  }
103  } while (sum);
104  }
105  // delete too small domains.
106  size_type nbmaxinsub = 0;
107  for (size_type i = 0; i < nbtotsub; ++i)
108  nbmaxinsub = std::max(nbmaxinsub, subs[i].size());
109 
110  std::fill(ns.begin(), ns.end(), size_type(0));
111  for (size_type i = 0; i < nbtotsub; ++i) {
112  if (subs[i].size() > 0 && subs[i].size() < nbmaxinsub / 10) {
113 
114  for (int k = 0; k < dim; ++k) nu[k] = ns[k];
115  size_type nbmax = 0, imax = 0;
116 
117  for (int l = 0; l < dim; ++l) {
118  nu[l]--;
119  for (int m = 0; m < 2; ++m, nu[l]+=2) {
120  bool ok = true;
121  for (int k = 0; k < dim && ok; ++k)
122  if (nu[k] >= nbsub[k]) ok = false;
123  if (ok) {
124  size_type ind = ns[0];
125  for (int k=1; k < dim; ++k) ind += ns[k]*mult[k];
126  if (subs[ind].size() > nbmax)
127  { nbmax = subs[ind].size(); imax = ind; }
128  }
129  }
130  nu[l]--;
131  }
132 
133  if (nbmax > subs[i].size()) {
134  for (map_type::iterator it=subs[i].begin(); it!=subs[i].end(); ++it)
135  subs[imax][it->first] = void_type();
136  subs[i].clear();
137  }
138  }
139  for (int k = 0; k < dim; ++k)
140  { ns[k]++; if (ns[k] < nbsub[k]) break; ns[k] = 0; }
141  }
142 
143  // delete empty domains.
144  size_type effnb = 0;
145  for (size_type i = 0; i < nbtotsub; ++i) {
146  if (subs[i].size() > 0)
147  { if (i != effnb) std::swap(subs[i], subs[effnb]); ++effnb; }
148  }
149 
150  // build matrices
151  subs.resize(effnb);
152  vB.resize(effnb);
153  for (size_type i = 0; i < effnb; ++i) {
154  clear(vB[i]); resize(vB[i], nbpts, subs[i].size());
155  size_type j = 0;
156  for (map_type::iterator it=subs[i].begin(); it!=subs[i].end(); ++it, ++j)
157  vB[i](it->first, j) = value_type(1);
158  }
159  }
160 
161 
162 }
163 
164 
165 #endif
size_t size_type
used as the common size type in the library
Definition: bgeot_poly.h:49
void rudimentary_regular_decomposition(std::vector< Point > pts, double msize, double overlap, std::vector< Matrix > &vB)
This function separates into small boxes of size msize with a ratio of overlap (in [0...
void resize(V &v, size_type n)
*/
Definition: gmm_blas.h:209
Include the base gmm files.
void clear(L &l)
clear (fill with zeros) a vector or matrix.
Definition: gmm_blas.h:59