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726 lines
24 KiB
726 lines
24 KiB
/* sstemr.f -- translated by f2c (version 20061008). |
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You must link the resulting object file with libf2c: |
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on Microsoft Windows system, link with libf2c.lib; |
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm |
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or, if you install libf2c.a in a standard place, with -lf2c -lm |
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-- in that order, at the end of the command line, as in |
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cc *.o -lf2c -lm |
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., |
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http://www.netlib.org/f2c/libf2c.zip |
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*/ |
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#include "clapack.h" |
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/* Table of constant values */ |
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static integer c__1 = 1; |
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static real c_b18 = .003f; |
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/* Subroutine */ int sstemr_(char *jobz, char *range, integer *n, real *d__, |
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real *e, real *vl, real *vu, integer *il, integer *iu, integer *m, |
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real *w, real *z__, integer *ldz, integer *nzc, integer *isuppz, |
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logical *tryrac, real *work, integer *lwork, integer *iwork, integer * |
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liwork, integer *info) |
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{ |
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/* System generated locals */ |
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integer z_dim1, z_offset, i__1, i__2; |
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real r__1, r__2; |
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/* Builtin functions */ |
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double sqrt(doublereal); |
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/* Local variables */ |
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integer i__, j; |
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real r1, r2; |
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integer jj; |
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real cs; |
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integer in; |
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real sn, wl, wu; |
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integer iil, iiu; |
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real eps, tmp; |
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integer indd, iend, jblk, wend; |
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real rmin, rmax; |
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integer itmp; |
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real tnrm; |
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integer inde2; |
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extern /* Subroutine */ int slae2_(real *, real *, real *, real *, real *) |
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; |
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integer itmp2; |
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real rtol1, rtol2, scale; |
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integer indgp; |
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extern logical lsame_(char *, char *); |
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integer iinfo; |
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extern /* Subroutine */ int sscal_(integer *, real *, real *, integer *); |
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integer iindw, ilast, lwmin; |
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extern /* Subroutine */ int scopy_(integer *, real *, integer *, real *, |
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integer *), sswap_(integer *, real *, integer *, real *, integer * |
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); |
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logical wantz; |
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extern /* Subroutine */ int slaev2_(real *, real *, real *, real *, real * |
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, real *, real *); |
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logical alleig; |
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integer ibegin; |
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logical indeig; |
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integer iindbl; |
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logical valeig; |
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extern doublereal slamch_(char *); |
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integer wbegin; |
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real safmin; |
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extern /* Subroutine */ int xerbla_(char *, integer *); |
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real bignum; |
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integer inderr, iindwk, indgrs, offset; |
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extern /* Subroutine */ int slarrc_(char *, integer *, real *, real *, |
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real *, real *, real *, integer *, integer *, integer *, integer * |
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), slarre_(char *, integer *, real *, real *, integer *, |
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integer *, real *, real *, real *, real *, real *, real *, |
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integer *, integer *, integer *, real *, real *, real *, integer * |
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, integer *, real *, real *, real *, integer *, integer *) |
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; |
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real thresh; |
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integer iinspl, indwrk, ifirst, liwmin, nzcmin; |
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real pivmin; |
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extern doublereal slanst_(char *, integer *, real *, real *); |
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extern /* Subroutine */ int slarrj_(integer *, real *, real *, integer *, |
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integer *, real *, integer *, real *, real *, real *, integer *, |
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real *, real *, integer *), slarrr_(integer *, real *, real *, |
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integer *); |
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integer nsplit; |
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extern /* Subroutine */ int slarrv_(integer *, real *, real *, real *, |
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real *, real *, integer *, integer *, integer *, integer *, real * |
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, real *, real *, real *, real *, real *, integer *, integer *, |
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real *, real *, integer *, integer *, real *, integer *, integer * |
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); |
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real smlnum; |
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extern /* Subroutine */ int slasrt_(char *, integer *, real *, integer *); |
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logical lquery, zquery; |
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/* -- LAPACK computational routine (version 3.2) -- */ |
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/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */ |
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/* November 2006 */ |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* SSTEMR computes selected eigenvalues and, optionally, eigenvectors */ |
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/* of a real symmetric tridiagonal matrix T. Any such unreduced matrix has */ |
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/* a well defined set of pairwise different real eigenvalues, the corresponding */ |
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/* real eigenvectors are pairwise orthogonal. */ |
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/* The spectrum may be computed either completely or partially by specifying */ |
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/* either an interval (VL,VU] or a range of indices IL:IU for the desired */ |
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/* eigenvalues. */ |
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/* Depending on the number of desired eigenvalues, these are computed either */ |
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/* by bisection or the dqds algorithm. Numerically orthogonal eigenvectors are */ |
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/* computed by the use of various suitable L D L^T factorizations near clusters */ |
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/* of close eigenvalues (referred to as RRRs, Relatively Robust */ |
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/* Representations). An informal sketch of the algorithm follows. */ |
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/* For each unreduced block (submatrix) of T, */ |
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/* (a) Compute T - sigma I = L D L^T, so that L and D */ |
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/* define all the wanted eigenvalues to high relative accuracy. */ |
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/* This means that small relative changes in the entries of D and L */ |
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/* cause only small relative changes in the eigenvalues and */ |
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/* eigenvectors. The standard (unfactored) representation of the */ |
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/* tridiagonal matrix T does not have this property in general. */ |
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/* (b) Compute the eigenvalues to suitable accuracy. */ |
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/* If the eigenvectors are desired, the algorithm attains full */ |
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/* accuracy of the computed eigenvalues only right before */ |
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/* the corresponding vectors have to be computed, see steps c) and d). */ |
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/* (c) For each cluster of close eigenvalues, select a new */ |
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/* shift close to the cluster, find a new factorization, and refine */ |
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/* the shifted eigenvalues to suitable accuracy. */ |
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/* (d) For each eigenvalue with a large enough relative separation compute */ |
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/* the corresponding eigenvector by forming a rank revealing twisted */ |
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/* factorization. Go back to (c) for any clusters that remain. */ |
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/* For more details, see: */ |
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/* - Inderjit S. Dhillon and Beresford N. Parlett: "Multiple representations */ |
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/* to compute orthogonal eigenvectors of symmetric tridiagonal matrices," */ |
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/* Linear Algebra and its Applications, 387(1), pp. 1-28, August 2004. */ |
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/* - Inderjit Dhillon and Beresford Parlett: "Orthogonal Eigenvectors and */ |
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/* Relative Gaps," SIAM Journal on Matrix Analysis and Applications, Vol. 25, */ |
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/* 2004. Also LAPACK Working Note 154. */ |
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/* - Inderjit Dhillon: "A new O(n^2) algorithm for the symmetric */ |
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/* tridiagonal eigenvalue/eigenvector problem", */ |
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/* Computer Science Division Technical Report No. UCB/CSD-97-971, */ |
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/* UC Berkeley, May 1997. */ |
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/* Notes: */ |
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/* 1.SSTEMR works only on machines which follow IEEE-754 */ |
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/* floating-point standard in their handling of infinities and NaNs. */ |
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/* This permits the use of efficient inner loops avoiding a check for */ |
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/* zero divisors. */ |
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/* Arguments */ |
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/* ========= */ |
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/* JOBZ (input) CHARACTER*1 */ |
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/* = 'N': Compute eigenvalues only; */ |
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/* = 'V': Compute eigenvalues and eigenvectors. */ |
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/* RANGE (input) CHARACTER*1 */ |
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/* = 'A': all eigenvalues will be found. */ |
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/* = 'V': all eigenvalues in the half-open interval (VL,VU] */ |
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/* will be found. */ |
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/* = 'I': the IL-th through IU-th eigenvalues will be found. */ |
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/* N (input) INTEGER */ |
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/* The order of the matrix. N >= 0. */ |
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/* D (input/output) REAL array, dimension (N) */ |
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/* On entry, the N diagonal elements of the tridiagonal matrix */ |
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/* T. On exit, D is overwritten. */ |
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/* E (input/output) REAL array, dimension (N) */ |
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/* On entry, the (N-1) subdiagonal elements of the tridiagonal */ |
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/* matrix T in elements 1 to N-1 of E. E(N) need not be set on */ |
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/* input, but is used internally as workspace. */ |
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/* On exit, E is overwritten. */ |
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/* VL (input) REAL */ |
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/* VU (input) REAL */ |
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/* If RANGE='V', the lower and upper bounds of the interval to */ |
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/* be searched for eigenvalues. VL < VU. */ |
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/* Not referenced if RANGE = 'A' or 'I'. */ |
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/* IL (input) INTEGER */ |
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/* IU (input) INTEGER */ |
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/* If RANGE='I', the indices (in ascending order) of the */ |
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/* smallest and largest eigenvalues to be returned. */ |
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/* 1 <= IL <= IU <= N, if N > 0. */ |
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/* Not referenced if RANGE = 'A' or 'V'. */ |
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/* M (output) INTEGER */ |
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/* The total number of eigenvalues found. 0 <= M <= N. */ |
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/* If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1. */ |
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/* W (output) REAL array, dimension (N) */ |
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/* The first M elements contain the selected eigenvalues in */ |
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/* ascending order. */ |
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/* Z (output) REAL array, dimension (LDZ, max(1,M) ) */ |
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/* If JOBZ = 'V', and if INFO = 0, then the first M columns of Z */ |
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/* contain the orthonormal eigenvectors of the matrix T */ |
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/* corresponding to the selected eigenvalues, with the i-th */ |
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/* column of Z holding the eigenvector associated with W(i). */ |
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/* If JOBZ = 'N', then Z is not referenced. */ |
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/* Note: the user must ensure that at least max(1,M) columns are */ |
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/* supplied in the array Z; if RANGE = 'V', the exact value of M */ |
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/* is not known in advance and can be computed with a workspace */ |
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/* query by setting NZC = -1, see below. */ |
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/* LDZ (input) INTEGER */ |
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/* The leading dimension of the array Z. LDZ >= 1, and if */ |
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/* JOBZ = 'V', then LDZ >= max(1,N). */ |
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/* NZC (input) INTEGER */ |
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/* The number of eigenvectors to be held in the array Z. */ |
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/* If RANGE = 'A', then NZC >= max(1,N). */ |
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/* If RANGE = 'V', then NZC >= the number of eigenvalues in (VL,VU]. */ |
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/* If RANGE = 'I', then NZC >= IU-IL+1. */ |
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/* If NZC = -1, then a workspace query is assumed; the */ |
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/* routine calculates the number of columns of the array Z that */ |
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/* are needed to hold the eigenvectors. */ |
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/* This value is returned as the first entry of the Z array, and */ |
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/* no error message related to NZC is issued by XERBLA. */ |
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/* ISUPPZ (output) INTEGER ARRAY, dimension ( 2*max(1,M) ) */ |
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/* The support of the eigenvectors in Z, i.e., the indices */ |
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/* indicating the nonzero elements in Z. The i-th computed eigenvector */ |
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/* is nonzero only in elements ISUPPZ( 2*i-1 ) through */ |
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/* ISUPPZ( 2*i ). This is relevant in the case when the matrix */ |
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/* is split. ISUPPZ is only accessed when JOBZ is 'V' and N > 0. */ |
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/* TRYRAC (input/output) LOGICAL */ |
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/* If TRYRAC.EQ..TRUE., indicates that the code should check whether */ |
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/* the tridiagonal matrix defines its eigenvalues to high relative */ |
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/* accuracy. If so, the code uses relative-accuracy preserving */ |
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/* algorithms that might be (a bit) slower depending on the matrix. */ |
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/* If the matrix does not define its eigenvalues to high relative */ |
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/* accuracy, the code can uses possibly faster algorithms. */ |
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/* If TRYRAC.EQ..FALSE., the code is not required to guarantee */ |
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/* relatively accurate eigenvalues and can use the fastest possible */ |
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/* techniques. */ |
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/* On exit, a .TRUE. TRYRAC will be set to .FALSE. if the matrix */ |
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/* does not define its eigenvalues to high relative accuracy. */ |
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/* WORK (workspace/output) REAL array, dimension (LWORK) */ |
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/* On exit, if INFO = 0, WORK(1) returns the optimal */ |
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/* (and minimal) LWORK. */ |
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/* LWORK (input) INTEGER */ |
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/* The dimension of the array WORK. LWORK >= max(1,18*N) */ |
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/* if JOBZ = 'V', and LWORK >= max(1,12*N) if JOBZ = 'N'. */ |
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/* If LWORK = -1, then a workspace query is assumed; the routine */ |
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/* only calculates the optimal size of the WORK array, returns */ |
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/* this value as the first entry of the WORK array, and no error */ |
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/* message related to LWORK is issued by XERBLA. */ |
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/* IWORK (workspace/output) INTEGER array, dimension (LIWORK) */ |
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/* On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK. */ |
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/* LIWORK (input) INTEGER */ |
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/* The dimension of the array IWORK. LIWORK >= max(1,10*N) */ |
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/* if the eigenvectors are desired, and LIWORK >= max(1,8*N) */ |
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/* if only the eigenvalues are to be computed. */ |
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/* If LIWORK = -1, then a workspace query is assumed; the */ |
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/* routine only calculates the optimal size of the IWORK array, */ |
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/* returns this value as the first entry of the IWORK array, and */ |
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/* no error message related to LIWORK is issued by XERBLA. */ |
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/* INFO (output) INTEGER */ |
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/* On exit, INFO */ |
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/* = 0: successful exit */ |
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/* < 0: if INFO = -i, the i-th argument had an illegal value */ |
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/* > 0: if INFO = 1X, internal error in SLARRE, */ |
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/* if INFO = 2X, internal error in SLARRV. */ |
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/* Here, the digit X = ABS( IINFO ) < 10, where IINFO is */ |
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/* the nonzero error code returned by SLARRE or */ |
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/* SLARRV, respectively. */ |
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/* Further Details */ |
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/* =============== */ |
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/* Based on contributions by */ |
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/* Beresford Parlett, University of California, Berkeley, USA */ |
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/* Jim Demmel, University of California, Berkeley, USA */ |
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/* Inderjit Dhillon, University of Texas, Austin, USA */ |
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/* Osni Marques, LBNL/NERSC, USA */ |
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/* Christof Voemel, University of California, Berkeley, USA */ |
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/* ===================================================================== */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* .. Executable Statements .. */ |
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/* Test the input parameters. */ |
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/* Parameter adjustments */ |
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--d__; |
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--e; |
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--w; |
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z_dim1 = *ldz; |
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z_offset = 1 + z_dim1; |
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z__ -= z_offset; |
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--isuppz; |
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--work; |
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--iwork; |
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/* Function Body */ |
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wantz = lsame_(jobz, "V"); |
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alleig = lsame_(range, "A"); |
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valeig = lsame_(range, "V"); |
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indeig = lsame_(range, "I"); |
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lquery = *lwork == -1 || *liwork == -1; |
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zquery = *nzc == -1; |
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/* SSTEMR needs WORK of size 6*N, IWORK of size 3*N. */ |
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/* In addition, SLARRE needs WORK of size 6*N, IWORK of size 5*N. */ |
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/* Furthermore, SLARRV needs WORK of size 12*N, IWORK of size 7*N. */ |
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if (wantz) { |
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lwmin = *n * 18; |
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liwmin = *n * 10; |
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} else { |
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/* need less workspace if only the eigenvalues are wanted */ |
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lwmin = *n * 12; |
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liwmin = *n << 3; |
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} |
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wl = 0.f; |
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wu = 0.f; |
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iil = 0; |
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iiu = 0; |
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if (valeig) { |
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/* We do not reference VL, VU in the cases RANGE = 'I','A' */ |
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/* The interval (WL, WU] contains all the wanted eigenvalues. */ |
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/* It is either given by the user or computed in SLARRE. */ |
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wl = *vl; |
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wu = *vu; |
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} else if (indeig) { |
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/* We do not reference IL, IU in the cases RANGE = 'V','A' */ |
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iil = *il; |
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iiu = *iu; |
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} |
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*info = 0; |
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if (! (wantz || lsame_(jobz, "N"))) { |
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*info = -1; |
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} else if (! (alleig || valeig || indeig)) { |
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*info = -2; |
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} else if (*n < 0) { |
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*info = -3; |
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} else if (valeig && *n > 0 && wu <= wl) { |
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*info = -7; |
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} else if (indeig && (iil < 1 || iil > *n)) { |
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*info = -8; |
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} else if (indeig && (iiu < iil || iiu > *n)) { |
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*info = -9; |
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} else if (*ldz < 1 || wantz && *ldz < *n) { |
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*info = -13; |
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} else if (*lwork < lwmin && ! lquery) { |
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*info = -17; |
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} else if (*liwork < liwmin && ! lquery) { |
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*info = -19; |
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} |
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/* Get machine constants. */ |
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safmin = slamch_("Safe minimum"); |
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eps = slamch_("Precision"); |
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smlnum = safmin / eps; |
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bignum = 1.f / smlnum; |
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rmin = sqrt(smlnum); |
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/* Computing MIN */ |
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r__1 = sqrt(bignum), r__2 = 1.f / sqrt(sqrt(safmin)); |
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rmax = dmin(r__1,r__2); |
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if (*info == 0) { |
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work[1] = (real) lwmin; |
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iwork[1] = liwmin; |
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if (wantz && alleig) { |
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nzcmin = *n; |
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} else if (wantz && valeig) { |
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slarrc_("T", n, vl, vu, &d__[1], &e[1], &safmin, &nzcmin, &itmp, & |
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itmp2, info); |
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} else if (wantz && indeig) { |
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nzcmin = iiu - iil + 1; |
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} else { |
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/* WANTZ .EQ. FALSE. */ |
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nzcmin = 0; |
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} |
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if (zquery && *info == 0) { |
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z__[z_dim1 + 1] = (real) nzcmin; |
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} else if (*nzc < nzcmin && ! zquery) { |
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*info = -14; |
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} |
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} |
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if (*info != 0) { |
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i__1 = -(*info); |
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xerbla_("SSTEMR", &i__1); |
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return 0; |
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} else if (lquery || zquery) { |
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return 0; |
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} |
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/* Handle N = 0, 1, and 2 cases immediately */ |
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*m = 0; |
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if (*n == 0) { |
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return 0; |
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} |
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if (*n == 1) { |
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if (alleig || indeig) { |
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*m = 1; |
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w[1] = d__[1]; |
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} else { |
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if (wl < d__[1] && wu >= d__[1]) { |
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*m = 1; |
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w[1] = d__[1]; |
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} |
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} |
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if (wantz && ! zquery) { |
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z__[z_dim1 + 1] = 1.f; |
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isuppz[1] = 1; |
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isuppz[2] = 1; |
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} |
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return 0; |
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} |
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if (*n == 2) { |
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if (! wantz) { |
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slae2_(&d__[1], &e[1], &d__[2], &r1, &r2); |
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} else if (wantz && ! zquery) { |
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slaev2_(&d__[1], &e[1], &d__[2], &r1, &r2, &cs, &sn); |
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} |
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if (alleig || valeig && r2 > wl && r2 <= wu || indeig && iil == 1) { |
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++(*m); |
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w[*m] = r2; |
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if (wantz && ! zquery) { |
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z__[*m * z_dim1 + 1] = -sn; |
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z__[*m * z_dim1 + 2] = cs; |
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/* Note: At most one of SN and CS can be zero. */ |
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if (sn != 0.f) { |
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if (cs != 0.f) { |
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isuppz[(*m << 1) - 1] = 1; |
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isuppz[(*m << 1) - 1] = 2; |
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} else { |
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isuppz[(*m << 1) - 1] = 1; |
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isuppz[(*m << 1) - 1] = 1; |
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} |
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} else { |
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isuppz[(*m << 1) - 1] = 2; |
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isuppz[*m * 2] = 2; |
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} |
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} |
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} |
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if (alleig || valeig && r1 > wl && r1 <= wu || indeig && iiu == 2) { |
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++(*m); |
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w[*m] = r1; |
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if (wantz && ! zquery) { |
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z__[*m * z_dim1 + 1] = cs; |
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z__[*m * z_dim1 + 2] = sn; |
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/* Note: At most one of SN and CS can be zero. */ |
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if (sn != 0.f) { |
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if (cs != 0.f) { |
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isuppz[(*m << 1) - 1] = 1; |
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isuppz[(*m << 1) - 1] = 2; |
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} else { |
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isuppz[(*m << 1) - 1] = 1; |
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isuppz[(*m << 1) - 1] = 1; |
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} |
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} else { |
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isuppz[(*m << 1) - 1] = 2; |
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isuppz[*m * 2] = 2; |
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} |
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} |
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} |
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return 0; |
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} |
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/* Continue with general N */ |
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indgrs = 1; |
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inderr = (*n << 1) + 1; |
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indgp = *n * 3 + 1; |
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indd = (*n << 2) + 1; |
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inde2 = *n * 5 + 1; |
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indwrk = *n * 6 + 1; |
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|
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iinspl = 1; |
|
iindbl = *n + 1; |
|
iindw = (*n << 1) + 1; |
|
iindwk = *n * 3 + 1; |
|
|
|
/* Scale matrix to allowable range, if necessary. */ |
|
/* The allowable range is related to the PIVMIN parameter; see the */ |
|
/* comments in SLARRD. The preference for scaling small values */ |
|
/* up is heuristic; we expect users' matrices not to be close to the */ |
|
/* RMAX threshold. */ |
|
|
|
scale = 1.f; |
|
tnrm = slanst_("M", n, &d__[1], &e[1]); |
|
if (tnrm > 0.f && tnrm < rmin) { |
|
scale = rmin / tnrm; |
|
} else if (tnrm > rmax) { |
|
scale = rmax / tnrm; |
|
} |
|
if (scale != 1.f) { |
|
sscal_(n, &scale, &d__[1], &c__1); |
|
i__1 = *n - 1; |
|
sscal_(&i__1, &scale, &e[1], &c__1); |
|
tnrm *= scale; |
|
if (valeig) { |
|
/* If eigenvalues in interval have to be found, */ |
|
/* scale (WL, WU] accordingly */ |
|
wl *= scale; |
|
wu *= scale; |
|
} |
|
} |
|
|
|
/* Compute the desired eigenvalues of the tridiagonal after splitting */ |
|
/* into smaller subblocks if the corresponding off-diagonal elements */ |
|
/* are small */ |
|
/* THRESH is the splitting parameter for SLARRE */ |
|
/* A negative THRESH forces the old splitting criterion based on the */ |
|
/* size of the off-diagonal. A positive THRESH switches to splitting */ |
|
/* which preserves relative accuracy. */ |
|
|
|
if (*tryrac) { |
|
/* Test whether the matrix warrants the more expensive relative approach. */ |
|
slarrr_(n, &d__[1], &e[1], &iinfo); |
|
} else { |
|
/* The user does not care about relative accurately eigenvalues */ |
|
iinfo = -1; |
|
} |
|
/* Set the splitting criterion */ |
|
if (iinfo == 0) { |
|
thresh = eps; |
|
} else { |
|
thresh = -eps; |
|
/* relative accuracy is desired but T does not guarantee it */ |
|
*tryrac = FALSE_; |
|
} |
|
|
|
if (*tryrac) { |
|
/* Copy original diagonal, needed to guarantee relative accuracy */ |
|
scopy_(n, &d__[1], &c__1, &work[indd], &c__1); |
|
} |
|
/* Store the squares of the offdiagonal values of T */ |
|
i__1 = *n - 1; |
|
for (j = 1; j <= i__1; ++j) { |
|
/* Computing 2nd power */ |
|
r__1 = e[j]; |
|
work[inde2 + j - 1] = r__1 * r__1; |
|
/* L5: */ |
|
} |
|
/* Set the tolerance parameters for bisection */ |
|
if (! wantz) { |
|
/* SLARRE computes the eigenvalues to full precision. */ |
|
rtol1 = eps * 4.f; |
|
rtol2 = eps * 4.f; |
|
} else { |
|
/* SLARRE computes the eigenvalues to less than full precision. */ |
|
/* SLARRV will refine the eigenvalue approximations, and we can */ |
|
/* need less accurate initial bisection in SLARRE. */ |
|
/* Note: these settings do only affect the subset case and SLARRE */ |
|
/* Computing MAX */ |
|
r__1 = sqrt(eps) * .05f, r__2 = eps * 4.f; |
|
rtol1 = dmax(r__1,r__2); |
|
/* Computing MAX */ |
|
r__1 = sqrt(eps) * .005f, r__2 = eps * 4.f; |
|
rtol2 = dmax(r__1,r__2); |
|
} |
|
slarre_(range, n, &wl, &wu, &iil, &iiu, &d__[1], &e[1], &work[inde2], & |
|
rtol1, &rtol2, &thresh, &nsplit, &iwork[iinspl], m, &w[1], &work[ |
|
inderr], &work[indgp], &iwork[iindbl], &iwork[iindw], &work[ |
|
indgrs], &pivmin, &work[indwrk], &iwork[iindwk], &iinfo); |
|
if (iinfo != 0) { |
|
*info = abs(iinfo) + 10; |
|
return 0; |
|
} |
|
/* Note that if RANGE .NE. 'V', SLARRE computes bounds on the desired */ |
|
/* part of the spectrum. All desired eigenvalues are contained in */ |
|
/* (WL,WU] */ |
|
if (wantz) { |
|
|
|
/* Compute the desired eigenvectors corresponding to the computed */ |
|
/* eigenvalues */ |
|
|
|
slarrv_(n, &wl, &wu, &d__[1], &e[1], &pivmin, &iwork[iinspl], m, & |
|
c__1, m, &c_b18, &rtol1, &rtol2, &w[1], &work[inderr], &work[ |
|
indgp], &iwork[iindbl], &iwork[iindw], &work[indgrs], &z__[ |
|
z_offset], ldz, &isuppz[1], &work[indwrk], &iwork[iindwk], & |
|
iinfo); |
|
if (iinfo != 0) { |
|
*info = abs(iinfo) + 20; |
|
return 0; |
|
} |
|
} else { |
|
/* SLARRE computes eigenvalues of the (shifted) root representation */ |
|
/* SLARRV returns the eigenvalues of the unshifted matrix. */ |
|
/* However, if the eigenvectors are not desired by the user, we need */ |
|
/* to apply the corresponding shifts from SLARRE to obtain the */ |
|
/* eigenvalues of the original matrix. */ |
|
i__1 = *m; |
|
for (j = 1; j <= i__1; ++j) { |
|
itmp = iwork[iindbl + j - 1]; |
|
w[j] += e[iwork[iinspl + itmp - 1]]; |
|
/* L20: */ |
|
} |
|
} |
|
|
|
if (*tryrac) { |
|
/* Refine computed eigenvalues so that they are relatively accurate */ |
|
/* with respect to the original matrix T. */ |
|
ibegin = 1; |
|
wbegin = 1; |
|
i__1 = iwork[iindbl + *m - 1]; |
|
for (jblk = 1; jblk <= i__1; ++jblk) { |
|
iend = iwork[iinspl + jblk - 1]; |
|
in = iend - ibegin + 1; |
|
wend = wbegin - 1; |
|
/* check if any eigenvalues have to be refined in this block */ |
|
L36: |
|
if (wend < *m) { |
|
if (iwork[iindbl + wend] == jblk) { |
|
++wend; |
|
goto L36; |
|
} |
|
} |
|
if (wend < wbegin) { |
|
ibegin = iend + 1; |
|
goto L39; |
|
} |
|
offset = iwork[iindw + wbegin - 1] - 1; |
|
ifirst = iwork[iindw + wbegin - 1]; |
|
ilast = iwork[iindw + wend - 1]; |
|
rtol2 = eps * 4.f; |
|
slarrj_(&in, &work[indd + ibegin - 1], &work[inde2 + ibegin - 1], |
|
&ifirst, &ilast, &rtol2, &offset, &w[wbegin], &work[ |
|
inderr + wbegin - 1], &work[indwrk], &iwork[iindwk], & |
|
pivmin, &tnrm, &iinfo); |
|
ibegin = iend + 1; |
|
wbegin = wend + 1; |
|
L39: |
|
; |
|
} |
|
} |
|
|
|
/* If matrix was scaled, then rescale eigenvalues appropriately. */ |
|
|
|
if (scale != 1.f) { |
|
r__1 = 1.f / scale; |
|
sscal_(m, &r__1, &w[1], &c__1); |
|
} |
|
|
|
/* If eigenvalues are not in increasing order, then sort them, */ |
|
/* possibly along with eigenvectors. */ |
|
|
|
if (nsplit > 1) { |
|
if (! wantz) { |
|
slasrt_("I", m, &w[1], &iinfo); |
|
if (iinfo != 0) { |
|
*info = 3; |
|
return 0; |
|
} |
|
} else { |
|
i__1 = *m - 1; |
|
for (j = 1; j <= i__1; ++j) { |
|
i__ = 0; |
|
tmp = w[j]; |
|
i__2 = *m; |
|
for (jj = j + 1; jj <= i__2; ++jj) { |
|
if (w[jj] < tmp) { |
|
i__ = jj; |
|
tmp = w[jj]; |
|
} |
|
/* L50: */ |
|
} |
|
if (i__ != 0) { |
|
w[i__] = w[j]; |
|
w[j] = tmp; |
|
if (wantz) { |
|
sswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[j * |
|
z_dim1 + 1], &c__1); |
|
itmp = isuppz[(i__ << 1) - 1]; |
|
isuppz[(i__ << 1) - 1] = isuppz[(j << 1) - 1]; |
|
isuppz[(j << 1) - 1] = itmp; |
|
itmp = isuppz[i__ * 2]; |
|
isuppz[i__ * 2] = isuppz[j * 2]; |
|
isuppz[j * 2] = itmp; |
|
} |
|
} |
|
/* L60: */ |
|
} |
|
} |
|
} |
|
|
|
|
|
work[1] = (real) lwmin; |
|
iwork[1] = liwmin; |
|
return 0; |
|
|
|
/* End of SSTEMR */ |
|
|
|
} /* sstemr_ */
|
|
|