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Diffstat (limited to 'Eigen/src/OrderingMethods/Amd.h')
| -rw-r--r-- | Eigen/src/OrderingMethods/Amd.h | 439 |
1 files changed, 439 insertions, 0 deletions
diff --git a/Eigen/src/OrderingMethods/Amd.h b/Eigen/src/OrderingMethods/Amd.h new file mode 100644 index 000000000..ce04852b8 --- /dev/null +++ b/Eigen/src/OrderingMethods/Amd.h @@ -0,0 +1,439 @@ +// This file is part of Eigen, a lightweight C++ template library +// for linear algebra. +// +// Copyright (C) 2010 Gael Guennebaud <gael.guennebaud@inria.fr> +// +// This Source Code Form is subject to the terms of the Mozilla +// Public License v. 2.0. If a copy of the MPL was not distributed +// with this file, You can obtain one at http://mozilla.org/MPL/2.0/. + +/* + +NOTE: this routine has been adapted from the CSparse library: + +Copyright (c) 2006, Timothy A. Davis. +http://www.cise.ufl.edu/research/sparse/CSparse + +CSparse is free software; you can redistribute it and/or +modify it under the terms of the GNU Lesser General Public +License as published by the Free Software Foundation; either +version 2.1 of the License, or (at your option) any later version. + +CSparse is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +Lesser General Public License for more details. + +You should have received a copy of the GNU Lesser General Public +License along with this Module; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + +*/ + +#include "../Core/util/NonMPL2.h" + +#ifndef EIGEN_SPARSE_AMD_H +#define EIGEN_SPARSE_AMD_H + +namespace Eigen { + +namespace internal { + +template<typename T> inline T amd_flip(const T& i) { return -i-2; } +template<typename T> inline T amd_unflip(const T& i) { return i<0 ? amd_flip(i) : i; } +template<typename T0, typename T1> inline bool amd_marked(const T0* w, const T1& j) { return w[j]<0; } +template<typename T0, typename T1> inline void amd_mark(const T0* w, const T1& j) { return w[j] = amd_flip(w[j]); } + +/* clear w */ +template<typename Index> +static int cs_wclear (Index mark, Index lemax, Index *w, Index n) +{ + Index k; + if(mark < 2 || (mark + lemax < 0)) + { + for(k = 0; k < n; k++) + if(w[k] != 0) + w[k] = 1; + mark = 2; + } + return (mark); /* at this point, w[0..n-1] < mark holds */ +} + +/* depth-first search and postorder of a tree rooted at node j */ +template<typename Index> +Index cs_tdfs(Index j, Index k, Index *head, const Index *next, Index *post, Index *stack) +{ + int i, p, top = 0; + if(!head || !next || !post || !stack) return (-1); /* check inputs */ + stack[0] = j; /* place j on the stack */ + while (top >= 0) /* while (stack is not empty) */ + { + p = stack[top]; /* p = top of stack */ + i = head[p]; /* i = youngest child of p */ + if(i == -1) + { + top--; /* p has no unordered children left */ + post[k++] = p; /* node p is the kth postordered node */ + } + else + { + head[p] = next[i]; /* remove i from children of p */ + stack[++top] = i; /* start dfs on child node i */ + } + } + return k; +} + + +/** \internal + * Approximate minimum degree ordering algorithm. + * \returns the permutation P reducing the fill-in of the input matrix \a C + * The input matrix \a C must be a selfadjoint compressed column major SparseMatrix object. Both the upper and lower parts have to be stored, but the diagonal entries are optional. + * On exit the values of C are destroyed */ +template<typename Scalar, typename Index> +void minimum_degree_ordering(SparseMatrix<Scalar,ColMajor,Index>& C, PermutationMatrix<Dynamic,Dynamic,Index>& perm) +{ + using std::sqrt; + typedef SparseMatrix<Scalar,ColMajor,Index> CCS; + + int d, dk, dext, lemax = 0, e, elenk, eln, i, j, k, k1, + k2, k3, jlast, ln, dense, nzmax, mindeg = 0, nvi, nvj, nvk, mark, wnvi, + ok, nel = 0, p, p1, p2, p3, p4, pj, pk, pk1, pk2, pn, q, t; + unsigned int h; + + Index n = C.cols(); + dense = std::max<Index> (16, Index(10 * sqrt(double(n)))); /* find dense threshold */ + dense = std::min<Index> (n-2, dense); + + Index cnz = C.nonZeros(); + perm.resize(n+1); + t = cnz + cnz/5 + 2*n; /* add elbow room to C */ + C.resizeNonZeros(t); + + Index* W = new Index[8*(n+1)]; /* get workspace */ + Index* len = W; + Index* nv = W + (n+1); + Index* next = W + 2*(n+1); + Index* head = W + 3*(n+1); + Index* elen = W + 4*(n+1); + Index* degree = W + 5*(n+1); + Index* w = W + 6*(n+1); + Index* hhead = W + 7*(n+1); + Index* last = perm.indices().data(); /* use P as workspace for last */ + + /* --- Initialize quotient graph ---------------------------------------- */ + Index* Cp = C.outerIndexPtr(); + Index* Ci = C.innerIndexPtr(); + for(k = 0; k < n; k++) + len[k] = Cp[k+1] - Cp[k]; + len[n] = 0; + nzmax = t; + + for(i = 0; i <= n; i++) + { + head[i] = -1; // degree list i is empty + last[i] = -1; + next[i] = -1; + hhead[i] = -1; // hash list i is empty + nv[i] = 1; // node i is just one node + w[i] = 1; // node i is alive + elen[i] = 0; // Ek of node i is empty + degree[i] = len[i]; // degree of node i + } + mark = internal::cs_wclear<Index>(0, 0, w, n); /* clear w */ + elen[n] = -2; /* n is a dead element */ + Cp[n] = -1; /* n is a root of assembly tree */ + w[n] = 0; /* n is a dead element */ + + /* --- Initialize degree lists ------------------------------------------ */ + for(i = 0; i < n; i++) + { + d = degree[i]; + if(d == 0) /* node i is empty */ + { + elen[i] = -2; /* element i is dead */ + nel++; + Cp[i] = -1; /* i is a root of assembly tree */ + w[i] = 0; + } + else if(d > dense) /* node i is dense */ + { + nv[i] = 0; /* absorb i into element n */ + elen[i] = -1; /* node i is dead */ + nel++; + Cp[i] = amd_flip (n); + nv[n]++; + } + else + { + if(head[d] != -1) last[head[d]] = i; + next[i] = head[d]; /* put node i in degree list d */ + head[d] = i; + } + } + + while (nel < n) /* while (selecting pivots) do */ + { + /* --- Select node of minimum approximate degree -------------------- */ + for(k = -1; mindeg < n && (k = head[mindeg]) == -1; mindeg++) {} + if(next[k] != -1) last[next[k]] = -1; + head[mindeg] = next[k]; /* remove k from degree list */ + elenk = elen[k]; /* elenk = |Ek| */ + nvk = nv[k]; /* # of nodes k represents */ + nel += nvk; /* nv[k] nodes of A eliminated */ + + /* --- Garbage collection ------------------------------------------- */ + if(elenk > 0 && cnz + mindeg >= nzmax) + { + for(j = 0; j < n; j++) + { + if((p = Cp[j]) >= 0) /* j is a live node or element */ + { + Cp[j] = Ci[p]; /* save first entry of object */ + Ci[p] = amd_flip (j); /* first entry is now amd_flip(j) */ + } + } + for(q = 0, p = 0; p < cnz; ) /* scan all of memory */ + { + if((j = amd_flip (Ci[p++])) >= 0) /* found object j */ + { + Ci[q] = Cp[j]; /* restore first entry of object */ + Cp[j] = q++; /* new pointer to object j */ + for(k3 = 0; k3 < len[j]-1; k3++) Ci[q++] = Ci[p++]; + } + } + cnz = q; /* Ci[cnz...nzmax-1] now free */ + } + + /* --- Construct new element ---------------------------------------- */ + dk = 0; + nv[k] = -nvk; /* flag k as in Lk */ + p = Cp[k]; + pk1 = (elenk == 0) ? p : cnz; /* do in place if elen[k] == 0 */ + pk2 = pk1; + for(k1 = 1; k1 <= elenk + 1; k1++) + { + if(k1 > elenk) + { + e = k; /* search the nodes in k */ + pj = p; /* list of nodes starts at Ci[pj]*/ + ln = len[k] - elenk; /* length of list of nodes in k */ + } + else + { + e = Ci[p++]; /* search the nodes in e */ + pj = Cp[e]; + ln = len[e]; /* length of list of nodes in e */ + } + for(k2 = 1; k2 <= ln; k2++) + { + i = Ci[pj++]; + if((nvi = nv[i]) <= 0) continue; /* node i dead, or seen */ + dk += nvi; /* degree[Lk] += size of node i */ + nv[i] = -nvi; /* negate nv[i] to denote i in Lk*/ + Ci[pk2++] = i; /* place i in Lk */ + if(next[i] != -1) last[next[i]] = last[i]; + if(last[i] != -1) /* remove i from degree list */ + { + next[last[i]] = next[i]; + } + else + { + head[degree[i]] = next[i]; + } + } + if(e != k) + { + Cp[e] = amd_flip (k); /* absorb e into k */ + w[e] = 0; /* e is now a dead element */ + } + } + if(elenk != 0) cnz = pk2; /* Ci[cnz...nzmax] is free */ + degree[k] = dk; /* external degree of k - |Lk\i| */ + Cp[k] = pk1; /* element k is in Ci[pk1..pk2-1] */ + len[k] = pk2 - pk1; + elen[k] = -2; /* k is now an element */ + + /* --- Find set differences ----------------------------------------- */ + mark = internal::cs_wclear<Index>(mark, lemax, w, n); /* clear w if necessary */ + for(pk = pk1; pk < pk2; pk++) /* scan 1: find |Le\Lk| */ + { + i = Ci[pk]; + if((eln = elen[i]) <= 0) continue;/* skip if elen[i] empty */ + nvi = -nv[i]; /* nv[i] was negated */ + wnvi = mark - nvi; + for(p = Cp[i]; p <= Cp[i] + eln - 1; p++) /* scan Ei */ + { + e = Ci[p]; + if(w[e] >= mark) + { + w[e] -= nvi; /* decrement |Le\Lk| */ + } + else if(w[e] != 0) /* ensure e is a live element */ + { + w[e] = degree[e] + wnvi; /* 1st time e seen in scan 1 */ + } + } + } + + /* --- Degree update ------------------------------------------------ */ + for(pk = pk1; pk < pk2; pk++) /* scan2: degree update */ + { + i = Ci[pk]; /* consider node i in Lk */ + p1 = Cp[i]; + p2 = p1 + elen[i] - 1; + pn = p1; + for(h = 0, d = 0, p = p1; p <= p2; p++) /* scan Ei */ + { + e = Ci[p]; + if(w[e] != 0) /* e is an unabsorbed element */ + { + dext = w[e] - mark; /* dext = |Le\Lk| */ + if(dext > 0) + { + d += dext; /* sum up the set differences */ + Ci[pn++] = e; /* keep e in Ei */ + h += e; /* compute the hash of node i */ + } + else + { + Cp[e] = amd_flip (k); /* aggressive absorb. e->k */ + w[e] = 0; /* e is a dead element */ + } + } + } + elen[i] = pn - p1 + 1; /* elen[i] = |Ei| */ + p3 = pn; + p4 = p1 + len[i]; + for(p = p2 + 1; p < p4; p++) /* prune edges in Ai */ + { + j = Ci[p]; + if((nvj = nv[j]) <= 0) continue; /* node j dead or in Lk */ + d += nvj; /* degree(i) += |j| */ + Ci[pn++] = j; /* place j in node list of i */ + h += j; /* compute hash for node i */ + } + if(d == 0) /* check for mass elimination */ + { + Cp[i] = amd_flip (k); /* absorb i into k */ + nvi = -nv[i]; + dk -= nvi; /* |Lk| -= |i| */ + nvk += nvi; /* |k| += nv[i] */ + nel += nvi; + nv[i] = 0; + elen[i] = -1; /* node i is dead */ + } + else + { + degree[i] = std::min<Index> (degree[i], d); /* update degree(i) */ + Ci[pn] = Ci[p3]; /* move first node to end */ + Ci[p3] = Ci[p1]; /* move 1st el. to end of Ei */ + Ci[p1] = k; /* add k as 1st element in of Ei */ + len[i] = pn - p1 + 1; /* new len of adj. list of node i */ + h %= n; /* finalize hash of i */ + next[i] = hhead[h]; /* place i in hash bucket */ + hhead[h] = i; + last[i] = h; /* save hash of i in last[i] */ + } + } /* scan2 is done */ + degree[k] = dk; /* finalize |Lk| */ + lemax = std::max<Index>(lemax, dk); + mark = internal::cs_wclear<Index>(mark+lemax, lemax, w, n); /* clear w */ + + /* --- Supernode detection ------------------------------------------ */ + for(pk = pk1; pk < pk2; pk++) + { + i = Ci[pk]; + if(nv[i] >= 0) continue; /* skip if i is dead */ + h = last[i]; /* scan hash bucket of node i */ + i = hhead[h]; + hhead[h] = -1; /* hash bucket will be empty */ + for(; i != -1 && next[i] != -1; i = next[i], mark++) + { + ln = len[i]; + eln = elen[i]; + for(p = Cp[i]+1; p <= Cp[i] + ln-1; p++) w[Ci[p]] = mark; + jlast = i; + for(j = next[i]; j != -1; ) /* compare i with all j */ + { + ok = (len[j] == ln) && (elen[j] == eln); + for(p = Cp[j] + 1; ok && p <= Cp[j] + ln - 1; p++) + { + if(w[Ci[p]] != mark) ok = 0; /* compare i and j*/ + } + if(ok) /* i and j are identical */ + { + Cp[j] = amd_flip (i); /* absorb j into i */ + nv[i] += nv[j]; + nv[j] = 0; + elen[j] = -1; /* node j is dead */ + j = next[j]; /* delete j from hash bucket */ + next[jlast] = j; + } + else + { + jlast = j; /* j and i are different */ + j = next[j]; + } + } + } + } + + /* --- Finalize new element------------------------------------------ */ + for(p = pk1, pk = pk1; pk < pk2; pk++) /* finalize Lk */ + { + i = Ci[pk]; + if((nvi = -nv[i]) <= 0) continue;/* skip if i is dead */ + nv[i] = nvi; /* restore nv[i] */ + d = degree[i] + dk - nvi; /* compute external degree(i) */ + d = std::min<Index> (d, n - nel - nvi); + if(head[d] != -1) last[head[d]] = i; + next[i] = head[d]; /* put i back in degree list */ + last[i] = -1; + head[d] = i; + mindeg = std::min<Index> (mindeg, d); /* find new minimum degree */ + degree[i] = d; + Ci[p++] = i; /* place i in Lk */ + } + nv[k] = nvk; /* # nodes absorbed into k */ + if((len[k] = p-pk1) == 0) /* length of adj list of element k*/ + { + Cp[k] = -1; /* k is a root of the tree */ + w[k] = 0; /* k is now a dead element */ + } + if(elenk != 0) cnz = p; /* free unused space in Lk */ + } + + /* --- Postordering ----------------------------------------------------- */ + for(i = 0; i < n; i++) Cp[i] = amd_flip (Cp[i]);/* fix assembly tree */ + for(j = 0; j <= n; j++) head[j] = -1; + for(j = n; j >= 0; j--) /* place unordered nodes in lists */ + { + if(nv[j] > 0) continue; /* skip if j is an element */ + next[j] = head[Cp[j]]; /* place j in list of its parent */ + head[Cp[j]] = j; + } + for(e = n; e >= 0; e--) /* place elements in lists */ + { + if(nv[e] <= 0) continue; /* skip unless e is an element */ + if(Cp[e] != -1) + { + next[e] = head[Cp[e]]; /* place e in list of its parent */ + head[Cp[e]] = e; + } + } + for(k = 0, i = 0; i <= n; i++) /* postorder the assembly tree */ + { + if(Cp[i] == -1) k = internal::cs_tdfs<Index>(i, k, head, next, perm.indices().data(), w); + } + + perm.indices().conservativeResize(n); + + delete[] W; +} + +} // namespace internal + +} // end namespace Eigen + +#endif // EIGEN_SPARSE_AMD_H |