SUBROUTINE SLASDT( N, LVL, ND, INODE, NDIML, NDIMR, MSUB ) * * -- LAPACK auxiliary routine (version 3.2.2) -- * -- LAPACK is a software package provided by Univ. of Tennessee, -- * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- * June 2010 * * .. Scalar Arguments .. INTEGER LVL, MSUB, N, ND * .. * .. Array Arguments .. INTEGER INODE( * ), NDIML( * ), NDIMR( * ) * .. * * Purpose * ======= * * SLASDT creates a tree of subproblems for bidiagonal divide and * conquer. * * Arguments * ========= * * N (input) INTEGER * On entry, the number of diagonal elements of the * bidiagonal matrix. * * LVL (output) INTEGER * On exit, the number of levels on the computation tree. * * ND (output) INTEGER * On exit, the number of nodes on the tree. * * INODE (output) INTEGER array, dimension ( N ) * On exit, centers of subproblems. * * NDIML (output) INTEGER array, dimension ( N ) * On exit, row dimensions of left children. * * NDIMR (output) INTEGER array, dimension ( N ) * On exit, row dimensions of right children. * * MSUB (input) INTEGER * On entry, the maximum row dimension each subproblem at the * bottom of the tree can be of. * * Further Details * =============== * * Based on contributions by * Ming Gu and Huan Ren, Computer Science Division, University of * California at Berkeley, USA * * ===================================================================== * * .. Parameters .. REAL TWO PARAMETER ( TWO = 2.0E+0 ) * .. * .. Local Scalars .. INTEGER I, IL, IR, LLST, MAXN, NCRNT, NLVL REAL TEMP * .. * .. Intrinsic Functions .. INTRINSIC INT, LOG, MAX, REAL * .. * .. Executable Statements .. * * Find the number of levels on the tree. * MAXN = MAX( 1, N ) TEMP = LOG( REAL( MAXN ) / REAL( MSUB+1 ) ) / LOG( TWO ) LVL = INT( TEMP ) + 1 * I = N / 2 INODE( 1 ) = I + 1 NDIML( 1 ) = I NDIMR( 1 ) = N - I - 1 IL = 0 IR = 1 LLST = 1 DO 20 NLVL = 1, LVL - 1 * * Constructing the tree at (NLVL+1)-st level. The number of * nodes created on this level is LLST * 2. * DO 10 I = 0, LLST - 1 IL = IL + 2 IR = IR + 2 NCRNT = LLST + I NDIML( IL ) = NDIML( NCRNT ) / 2 NDIMR( IL ) = NDIML( NCRNT ) - NDIML( IL ) - 1 INODE( IL ) = INODE( NCRNT ) - NDIMR( IL ) - 1 NDIML( IR ) = NDIMR( NCRNT ) / 2 NDIMR( IR ) = NDIMR( NCRNT ) - NDIML( IR ) - 1 INODE( IR ) = INODE( NCRNT ) + NDIML( IR ) + 1 10 CONTINUE LLST = LLST*2 20 CONTINUE ND = LLST*2 - 1 * RETURN * * End of SLASDT * END