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author | Shashank | 2017-05-29 12:40:26 +0530 |
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committer | Shashank | 2017-05-29 12:40:26 +0530 |
commit | 0345245e860375a32c9a437c4a9d9cae807134e9 (patch) | |
tree | ad51ecbfa7bcd3cc5f09834f1bb8c08feaa526a4 /usr/include/btf.h | |
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CMSCOPE changed
Diffstat (limited to 'usr/include/btf.h')
-rwxr-xr-x | usr/include/btf.h | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/usr/include/btf.h b/usr/include/btf.h new file mode 100755 index 000000000..9e823ae4f --- /dev/null +++ b/usr/include/btf.h @@ -0,0 +1,267 @@ +/* ========================================================================== */ +/* === BTF package ========================================================== */ +/* ========================================================================== */ + +/* BTF_MAXTRANS: find a column permutation Q to give A*Q a zero-free diagonal + * BTF_STRONGCOMP: find a symmetric permutation P to put P*A*P' into block + * upper triangular form. + * BTF_ORDER: do both of the above (btf_maxtrans then btf_strongcomp). + * + * By Tim Davis. Copyright (c) 2004-2007, University of Florida. + * with support from Sandia National Laboratories. All Rights Reserved. + */ + + +/* ========================================================================== */ +/* === BTF_MAXTRANS ========================================================= */ +/* ========================================================================== */ + +/* BTF_MAXTRANS: finds a permutation of the columns of a matrix so that it has a + * zero-free diagonal. The input is an m-by-n sparse matrix in compressed + * column form. The array Ap of size n+1 gives the starting and ending + * positions of the columns in the array Ai. Ap[0] must be zero. The array Ai + * contains the row indices of the nonzeros of the matrix A, and is of size + * Ap[n]. The row indices of column j are located in Ai[Ap[j] ... Ap[j+1]-1]. + * Row indices must be in the range 0 to m-1. Duplicate entries may be present + * in any given column. The input matrix is not checked for validity (row + * indices out of the range 0 to m-1 will lead to an undeterminate result - + * possibly a core dump, for example). Row indices in any given column need + * not be in sorted order. However, if they are sorted and the matrix already + * has a zero-free diagonal, then the identity permutation is returned. + * + * The output of btf_maxtrans is an array Match of size n. If row i is matched + * with column j, then A(i,j) is nonzero, and then Match[i] = j. If the matrix + * is structurally nonsingular, all entries in the Match array are unique, and + * Match can be viewed as a column permutation if A is square. That is, column + * k of the original matrix becomes column Match[k] of the permuted matrix. In + * MATLAB, this can be expressed as (for non-structurally singular matrices): + * + * Match = maxtrans (A) ; + * B = A (:, Match) ; + * + * except of course here the A matrix and Match vector are all 0-based (rows + * and columns in the range 0 to n-1), not 1-based (rows/cols in range 1 to n). + * The MATLAB dmperm routine returns a row permutation. See the maxtrans + * mexFunction for more details. + * + * If row i is not matched to any column, then Match[i] is == -1. The + * btf_maxtrans routine returns the number of nonzeros on diagonal of the + * permuted matrix. + * + * In the MATLAB mexFunction interface to btf_maxtrans, 1 is added to the Match + * array to obtain a 1-based permutation. Thus, in MATLAB where A is m-by-n: + * + * q = maxtrans (A) ; % has entries in the range 0:n + * q % a column permutation (only if sprank(A)==n) + * B = A (:, q) ; % permuted matrix (only if sprank(A)==n) + * sum (q > 0) ; % same as "sprank (A)" + * + * This behaviour differs from p = dmperm (A) in MATLAB, which returns the + * matching as p(j)=i if row i and column j are matched, and p(j)=0 if column j + * is unmatched. + * + * p = dmperm (A) ; % has entries in the range 0:m + * p % a row permutation (only if sprank(A)==m) + * B = A (p, :) ; % permuted matrix (only if sprank(A)==m) + * sum (p > 0) ; % definition of sprank (A) + * + * This algorithm is based on the paper "On Algorithms for obtaining a maximum + * transversal" by Iain Duff, ACM Trans. Mathematical Software, vol 7, no. 1, + * pp. 315-330, and "Algorithm 575: Permutations for a zero-free diagonal", + * same issue, pp. 387-390. Algorithm 575 is MC21A in the Harwell Subroutine + * Library. This code is not merely a translation of the Fortran code into C. + * It is a completely new implementation of the basic underlying method (depth + * first search over a subgraph with nodes corresponding to columns matched so + * far, and cheap matching). This code was written with minimal observation of + * the MC21A/B code itself. See comments below for a comparison between the + * maxtrans and MC21A/B codes. + * + * This routine operates on a column-form matrix and produces a column + * permutation. MC21A uses a row-form matrix and produces a row permutation. + * The difference is merely one of convention in the comments and interpretation + * of the inputs and outputs. If you want a row permutation, simply pass a + * compressed-row sparse matrix to this routine and you will get a row + * permutation (just like MC21A). Similarly, you can pass a column-oriented + * matrix to MC21A and it will happily return a column permutation. + */ + +#ifndef _BTF_H +#define _BTF_H + +/* make it easy for C++ programs to include BTF */ +#ifdef __cplusplus +extern "C" { +#endif + +#include "SuiteSparse_config.h" + +int btf_maxtrans /* returns # of columns matched */ +( + /* --- input, not modified: --- */ + int nrow, /* A is nrow-by-ncol in compressed column form */ + int ncol, + int Ap [ ], /* size ncol+1 */ + int Ai [ ], /* size nz = Ap [ncol] */ + double maxwork, /* maximum amount of work to do is maxwork*nnz(A); no limit + * if <= 0 */ + + /* --- output, not defined on input --- */ + double *work, /* work = -1 if maxwork > 0 and the total work performed + * reached the maximum of maxwork*nnz(A). + * Otherwise, work = the total work performed. */ + + int Match [ ], /* size nrow. Match [i] = j if column j matched to row i + * (see above for the singular-matrix case) */ + + /* --- workspace, not defined on input or output --- */ + int Work [ ] /* size 5*ncol */ +) ; + +/* long integer version (all "int" parameters become "SuiteSparse_long") */ +SuiteSparse_long btf_l_maxtrans (SuiteSparse_long, SuiteSparse_long, + SuiteSparse_long *, SuiteSparse_long *, double, double *, + SuiteSparse_long *, SuiteSparse_long *) ; + + +/* ========================================================================== */ +/* === BTF_STRONGCOMP ======================================================= */ +/* ========================================================================== */ + +/* BTF_STRONGCOMP finds the strongly connected components of a graph, returning + * a symmetric permutation. The matrix A must be square, and is provided on + * input in compressed-column form (see BTF_MAXTRANS, above). The diagonal of + * the input matrix A (or A*Q if Q is provided on input) is ignored. + * + * If Q is not NULL on input, then the strongly connected components of A*Q are + * found. Q may be flagged on input, where Q[k] < 0 denotes a flagged column k. + * The permutation is j = BTF_UNFLIP (Q [k]). On output, Q is modified (the + * flags are preserved) so that P*A*Q is in block upper triangular form. + * + * If Q is NULL, then the permutation P is returned so that P*A*P' is in upper + * block triangular form. + * + * The vector R gives the block boundaries, where block b is in rows/columns + * R[b] to R[b+1]-1 of the permuted matrix, and where b ranges from 1 to the + * number of strongly connected components found. + */ + +int btf_strongcomp /* return # of strongly connected components */ +( + /* input, not modified: */ + int n, /* A is n-by-n in compressed column form */ + int Ap [ ], /* size n+1 */ + int Ai [ ], /* size nz = Ap [n] */ + + /* optional input, modified (if present) on output: */ + int Q [ ], /* size n, input column permutation */ + + /* output, not defined on input */ + int P [ ], /* size n. P [k] = j if row and column j are kth row/col + * in permuted matrix. */ + + int R [ ], /* size n+1. block b is in rows/cols R[b] ... R[b+1]-1 */ + + /* workspace, not defined on input or output */ + int Work [ ] /* size 4n */ +) ; + +SuiteSparse_long btf_l_strongcomp (SuiteSparse_long, SuiteSparse_long *, + SuiteSparse_long *, SuiteSparse_long *, SuiteSparse_long *, + SuiteSparse_long *, SuiteSparse_long *) ; + + +/* ========================================================================== */ +/* === BTF_ORDER ============================================================ */ +/* ========================================================================== */ + +/* BTF_ORDER permutes a square matrix into upper block triangular form. It + * does this by first finding a maximum matching (or perhaps a limited matching + * if the work is limited), via the btf_maxtrans function. If a complete + * matching is not found, BTF_ORDER completes the permutation, but flags the + * columns of P*A*Q to denote which columns are not matched. If the matrix is + * structurally rank deficient, some of the entries on the diagonal of the + * permuted matrix will be zero. BTF_ORDER then calls btf_strongcomp to find + * the strongly-connected components. + * + * On output, P and Q are the row and column permutations, where i = P[k] if + * row i of A is the kth row of P*A*Q, and j = BTF_UNFLIP(Q[k]) if column j of + * A is the kth column of P*A*Q. If Q[k] < 0, then the (k,k)th entry in P*A*Q + * is structurally zero. + * + * The vector R gives the block boundaries, where block b is in rows/columns + * R[b] to R[b+1]-1 of the permuted matrix, and where b ranges from 1 to the + * number of strongly connected components found. + */ + +int btf_order /* returns number of blocks found */ +( + /* --- input, not modified: --- */ + int n, /* A is n-by-n in compressed column form */ + int Ap [ ], /* size n+1 */ + int Ai [ ], /* size nz = Ap [n] */ + double maxwork, /* do at most maxwork*nnz(A) work in the maximum + * transversal; no limit if <= 0 */ + + /* --- output, not defined on input --- */ + double *work, /* return value from btf_maxtrans */ + int P [ ], /* size n, row permutation */ + int Q [ ], /* size n, column permutation */ + int R [ ], /* size n+1. block b is in rows/cols R[b] ... R[b+1]-1 */ + int *nmatch, /* # nonzeros on diagonal of P*A*Q */ + + /* --- workspace, not defined on input or output --- */ + int Work [ ] /* size 5n */ +) ; + +SuiteSparse_long btf_l_order (SuiteSparse_long, SuiteSparse_long *, + SuiteSparse_long *, double , double *, SuiteSparse_long *, + SuiteSparse_long *, SuiteSparse_long *, SuiteSparse_long *, + SuiteSparse_long *) ; + + +/* ========================================================================== */ +/* === BTF marking of singular columns ====================================== */ +/* ========================================================================== */ + +/* BTF_FLIP is a "negation about -1", and is used to mark an integer j + * that is normally non-negative. BTF_FLIP (-1) is -1. BTF_FLIP of + * a number > -1 is negative, and BTF_FLIP of a number < -1 is positive. + * BTF_FLIP (BTF_FLIP (j)) = j for all integers j. UNFLIP (j) acts + * like an "absolute value" operation, and is always >= -1. You can test + * whether or not an integer j is "flipped" with the BTF_ISFLIPPED (j) + * macro. + */ + +#define BTF_FLIP(j) (-(j)-2) +#define BTF_ISFLIPPED(j) ((j) < -1) +#define BTF_UNFLIP(j) ((BTF_ISFLIPPED (j)) ? BTF_FLIP (j) : (j)) + +/* ========================================================================== */ +/* === BTF version ========================================================== */ +/* ========================================================================== */ + +/* All versions of BTF include these definitions. + * As an example, to test if the version you are using is 1.2 or later: + * + * if (BTF_VERSION >= BTF_VERSION_CODE (1,2)) ... + * + * This also works during compile-time: + * + * #if (BTF >= BTF_VERSION_CODE (1,2)) + * printf ("This is version 1.2 or later\n") ; + * #else + * printf ("This is an early version\n") ; + * #endif + */ + +#define BTF_DATE "Jun 1, 2012" +#define BTF_VERSION_CODE(main,sub) ((main) * 1000 + (sub)) +#define BTF_MAIN_VERSION 1 +#define BTF_SUB_VERSION 2 +#define BTF_SUBSUB_VERSION 0 +#define BTF_VERSION BTF_VERSION_CODE(BTF_MAIN_VERSION,BTF_SUB_VERSION) + +#ifdef __cplusplus +} +#endif +#endif |