124 lines
3.0 KiB
C
124 lines
3.0 KiB
C
|
#include "clapack.h"
|
||
|
|
|
||
|
|
/* Subroutine */ int dlasdt_(integer *n, integer *lvl, integer *nd, integer *
|
||
|
|
inode, integer *ndiml, integer *ndimr, integer *msub)
|
||
|
|
{
|
||
|
|
/* System generated locals */
|
||
|
|
integer i__1, i__2;
|
||
|
|
|
||
|
|
/* Builtin functions */
|
||
|
|
double log(doublereal);
|
||
|
|
|
||
|
|
/* Local variables */
|
||
|
|
integer i__, il, ir, maxn;
|
||
|
|
doublereal temp;
|
||
|
|
integer nlvl, llst, ncrnt;
|
||
|
|
|
||
|
|
|
||
|
|
/* -- LAPACK auxiliary routine (version 3.1) -- */
|
||
|
|
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
|
||
|
|
/* November 2006 */
|
||
|
|
|
||
|
|
/* .. Scalar Arguments .. */
|
||
|
|
/* .. */
|
||
|
|
/* .. Array Arguments .. */
|
||
|
|
/* .. */
|
||
|
|
|
||
|
|
/* Purpose */
|
||
|
|
/* ======= */
|
||
|
|
|
||
|
|
/* DLASDT 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 .. */
|
||
|
|
/* .. */
|
||
|
|
/* .. Local Scalars .. */
|
||
|
|
/* .. */
|
||
|
|
/* .. Intrinsic Functions .. */
|
||
|
|
/* .. */
|
||
|
|
/* .. Executable Statements .. */
|
||
|
|
|
||
|
|
/* Find the number of levels on the tree. */
|
||
|
|
|
||
|
|
/* Parameter adjustments */
|
||
|
|
--ndimr;
|
||
|
|
--ndiml;
|
||
|
|
--inode;
|
||
|
|
|
||
|
|
/* Function Body */
|
||
|
|
maxn = max(1,*n);
|
||
|
|
temp = log((doublereal) maxn / (doublereal) (*msub + 1)) / log(2.);
|
||
|
|
*lvl = (integer) temp + 1;
|
||
|
|
|
||
|
|
i__ = *n / 2;
|
||
|
|
inode[1] = i__ + 1;
|
||
|
|
ndiml[1] = i__;
|
||
|
|
ndimr[1] = *n - i__ - 1;
|
||
|
|
il = 0;
|
||
|
|
ir = 1;
|
||
|
|
llst = 1;
|
||
|
|
i__1 = *lvl - 1;
|
||
|
|
for (nlvl = 1; nlvl <= i__1; ++nlvl) {
|
||
|
|
|
||
|
|
/* Constructing the tree at (NLVL+1)-st level. The number of */
|
||
|
|
/* nodes created on this level is LLST * 2. */
|
||
|
|
|
||
|
|
i__2 = llst - 1;
|
||
|
|
for (i__ = 0; i__ <= i__2; ++i__) {
|
||
|
|
il += 2;
|
||
|
|
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;
|
||
|
|
/* L10: */
|
||
|
|
}
|
||
|
|
llst <<= 1;
|
||
|
|
/* L20: */
|
||
|
|
}
|
||
|
|
*nd = (llst << 1) - 1;
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
/* End of DLASDT */
|
||
|
|
|
||
|
|
} /* dlasdt_ */
|