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LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
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00001 *> \brief <b> SSTEVR computes the eigenvalues and, optionally, the left and/or right eigenvectors for OTHER matrices</b> 00002 * 00003 * =========== DOCUMENTATION =========== 00004 * 00005 * Online html documentation available at 00006 * http://www.netlib.org/lapack/explore-html/ 00007 * 00008 *> \htmlonly 00009 *> Download SSTEVR + dependencies 00010 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/sstevr.f"> 00011 *> [TGZ]</a> 00012 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/sstevr.f"> 00013 *> [ZIP]</a> 00014 *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/sstevr.f"> 00015 *> [TXT]</a> 00016 *> \endhtmlonly 00017 * 00018 * Definition: 00019 * =========== 00020 * 00021 * SUBROUTINE SSTEVR( JOBZ, RANGE, N, D, E, VL, VU, IL, IU, ABSTOL, 00022 * M, W, Z, LDZ, ISUPPZ, WORK, LWORK, IWORK, 00023 * LIWORK, INFO ) 00024 * 00025 * .. Scalar Arguments .. 00026 * CHARACTER JOBZ, RANGE 00027 * INTEGER IL, INFO, IU, LDZ, LIWORK, LWORK, M, N 00028 * REAL ABSTOL, VL, VU 00029 * .. 00030 * .. Array Arguments .. 00031 * INTEGER ISUPPZ( * ), IWORK( * ) 00032 * REAL D( * ), E( * ), W( * ), WORK( * ), Z( LDZ, * ) 00033 * .. 00034 * 00035 * 00036 *> \par Purpose: 00037 * ============= 00038 *> 00039 *> \verbatim 00040 *> 00041 *> SSTEVR computes selected eigenvalues and, optionally, eigenvectors 00042 *> of a real symmetric tridiagonal matrix T. Eigenvalues and 00043 *> eigenvectors can be selected by specifying either a range of values 00044 *> or a range of indices for the desired eigenvalues. 00045 *> 00046 *> Whenever possible, SSTEVR calls SSTEMR to compute the 00047 *> eigenspectrum using Relatively Robust Representations. SSTEMR 00048 *> computes eigenvalues by the dqds algorithm, while orthogonal 00049 *> eigenvectors are computed from various "good" L D L^T representations 00050 *> (also known as Relatively Robust Representations). Gram-Schmidt 00051 *> orthogonalization is avoided as far as possible. More specifically, 00052 *> the various steps of the algorithm are as follows. For the i-th 00053 *> unreduced block of T, 00054 *> (a) Compute T - sigma_i = L_i D_i L_i^T, such that L_i D_i L_i^T 00055 *> is a relatively robust representation, 00056 *> (b) Compute the eigenvalues, lambda_j, of L_i D_i L_i^T to high 00057 *> relative accuracy by the dqds algorithm, 00058 *> (c) If there is a cluster of close eigenvalues, "choose" sigma_i 00059 *> close to the cluster, and go to step (a), 00060 *> (d) Given the approximate eigenvalue lambda_j of L_i D_i L_i^T, 00061 *> compute the corresponding eigenvector by forming a 00062 *> rank-revealing twisted factorization. 00063 *> The desired accuracy of the output can be specified by the input 00064 *> parameter ABSTOL. 00065 *> 00066 *> For more details, see "A new O(n^2) algorithm for the symmetric 00067 *> tridiagonal eigenvalue/eigenvector problem", by Inderjit Dhillon, 00068 *> Computer Science Division Technical Report No. UCB//CSD-97-971, 00069 *> UC Berkeley, May 1997. 00070 *> 00071 *> 00072 *> Note 1 : SSTEVR calls SSTEMR when the full spectrum is requested 00073 *> on machines which conform to the ieee-754 floating point standard. 00074 *> SSTEVR calls SSTEBZ and SSTEIN on non-ieee machines and 00075 *> when partial spectrum requests are made. 00076 *> 00077 *> Normal execution of SSTEMR may create NaNs and infinities and 00078 *> hence may abort due to a floating point exception in environments 00079 *> which do not handle NaNs and infinities in the ieee standard default 00080 *> manner. 00081 *> \endverbatim 00082 * 00083 * Arguments: 00084 * ========== 00085 * 00086 *> \param[in] JOBZ 00087 *> \verbatim 00088 *> JOBZ is CHARACTER*1 00089 *> = 'N': Compute eigenvalues only; 00090 *> = 'V': Compute eigenvalues and eigenvectors. 00091 *> \endverbatim 00092 *> 00093 *> \param[in] RANGE 00094 *> \verbatim 00095 *> RANGE is CHARACTER*1 00096 *> = 'A': all eigenvalues will be found. 00097 *> = 'V': all eigenvalues in the half-open interval (VL,VU] 00098 *> will be found. 00099 *> = 'I': the IL-th through IU-th eigenvalues will be found. 00100 *> For RANGE = 'V' or 'I' and IU - IL < N - 1, SSTEBZ and 00101 *> SSTEIN are called 00102 *> \endverbatim 00103 *> 00104 *> \param[in] N 00105 *> \verbatim 00106 *> N is INTEGER 00107 *> The order of the matrix. N >= 0. 00108 *> \endverbatim 00109 *> 00110 *> \param[in,out] D 00111 *> \verbatim 00112 *> D is REAL array, dimension (N) 00113 *> On entry, the n diagonal elements of the tridiagonal matrix 00114 *> A. 00115 *> On exit, D may be multiplied by a constant factor chosen 00116 *> to avoid over/underflow in computing the eigenvalues. 00117 *> \endverbatim 00118 *> 00119 *> \param[in,out] E 00120 *> \verbatim 00121 *> E is REAL array, dimension (max(1,N-1)) 00122 *> On entry, the (n-1) subdiagonal elements of the tridiagonal 00123 *> matrix A in elements 1 to N-1 of E. 00124 *> On exit, E may be multiplied by a constant factor chosen 00125 *> to avoid over/underflow in computing the eigenvalues. 00126 *> \endverbatim 00127 *> 00128 *> \param[in] VL 00129 *> \verbatim 00130 *> VL is REAL 00131 *> \endverbatim 00132 *> 00133 *> \param[in] VU 00134 *> \verbatim 00135 *> VU is REAL 00136 *> If RANGE='V', the lower and upper bounds of the interval to 00137 *> be searched for eigenvalues. VL < VU. 00138 *> Not referenced if RANGE = 'A' or 'I'. 00139 *> \endverbatim 00140 *> 00141 *> \param[in] IL 00142 *> \verbatim 00143 *> IL is INTEGER 00144 *> \endverbatim 00145 *> 00146 *> \param[in] IU 00147 *> \verbatim 00148 *> IU is INTEGER 00149 *> If RANGE='I', the indices (in ascending order) of the 00150 *> smallest and largest eigenvalues to be returned. 00151 *> 1 <= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0. 00152 *> Not referenced if RANGE = 'A' or 'V'. 00153 *> \endverbatim 00154 *> 00155 *> \param[in] ABSTOL 00156 *> \verbatim 00157 *> ABSTOL is REAL 00158 *> The absolute error tolerance for the eigenvalues. 00159 *> An approximate eigenvalue is accepted as converged 00160 *> when it is determined to lie in an interval [a,b] 00161 *> of width less than or equal to 00162 *> 00163 *> ABSTOL + EPS * max( |a|,|b| ) , 00164 *> 00165 *> where EPS is the machine precision. If ABSTOL is less than 00166 *> or equal to zero, then EPS*|T| will be used in its place, 00167 *> where |T| is the 1-norm of the tridiagonal matrix obtained 00168 *> by reducing A to tridiagonal form. 00169 *> 00170 *> See "Computing Small Singular Values of Bidiagonal Matrices 00171 *> with Guaranteed High Relative Accuracy," by Demmel and 00172 *> Kahan, LAPACK Working Note #3. 00173 *> 00174 *> If high relative accuracy is important, set ABSTOL to 00175 *> SLAMCH( 'Safe minimum' ). Doing so will guarantee that 00176 *> eigenvalues are computed to high relative accuracy when 00177 *> possible in future releases. The current code does not 00178 *> make any guarantees about high relative accuracy, but 00179 *> future releases will. See J. Barlow and J. Demmel, 00180 *> "Computing Accurate Eigensystems of Scaled Diagonally 00181 *> Dominant Matrices", LAPACK Working Note #7, for a discussion 00182 *> of which matrices define their eigenvalues to high relative 00183 *> accuracy. 00184 *> \endverbatim 00185 *> 00186 *> \param[out] M 00187 *> \verbatim 00188 *> M is INTEGER 00189 *> The total number of eigenvalues found. 0 <= M <= N. 00190 *> If RANGE = 'A', M = N, and if RANGE = 'I', M = IU-IL+1. 00191 *> \endverbatim 00192 *> 00193 *> \param[out] W 00194 *> \verbatim 00195 *> W is REAL array, dimension (N) 00196 *> The first M elements contain the selected eigenvalues in 00197 *> ascending order. 00198 *> \endverbatim 00199 *> 00200 *> \param[out] Z 00201 *> \verbatim 00202 *> Z is REAL array, dimension (LDZ, max(1,M) ) 00203 *> If JOBZ = 'V', then if INFO = 0, the first M columns of Z 00204 *> contain the orthonormal eigenvectors of the matrix A 00205 *> corresponding to the selected eigenvalues, with the i-th 00206 *> column of Z holding the eigenvector associated with W(i). 00207 *> Note: the user must ensure that at least max(1,M) columns are 00208 *> supplied in the array Z; if RANGE = 'V', the exact value of M 00209 *> is not known in advance and an upper bound must be used. 00210 *> \endverbatim 00211 *> 00212 *> \param[in] LDZ 00213 *> \verbatim 00214 *> LDZ is INTEGER 00215 *> The leading dimension of the array Z. LDZ >= 1, and if 00216 *> JOBZ = 'V', LDZ >= max(1,N). 00217 *> \endverbatim 00218 *> 00219 *> \param[out] ISUPPZ 00220 *> \verbatim 00221 *> ISUPPZ is INTEGER array, dimension ( 2*max(1,M) ) 00222 *> The support of the eigenvectors in Z, i.e., the indices 00223 *> indicating the nonzero elements in Z. The i-th eigenvector 00224 *> is nonzero only in elements ISUPPZ( 2*i-1 ) through 00225 *> ISUPPZ( 2*i ). 00226 *> Implemented only for RANGE = 'A' or 'I' and IU - IL = N - 1 00227 *> \endverbatim 00228 *> 00229 *> \param[out] WORK 00230 *> \verbatim 00231 *> WORK is REAL array, dimension (MAX(1,LWORK)) 00232 *> On exit, if INFO = 0, WORK(1) returns the optimal (and 00233 *> minimal) LWORK. 00234 *> \endverbatim 00235 *> 00236 *> \param[in] LWORK 00237 *> \verbatim 00238 *> LWORK is INTEGER 00239 *> The dimension of the array WORK. LWORK >= 20*N. 00240 *> 00241 *> If LWORK = -1, then a workspace query is assumed; the routine 00242 *> only calculates the optimal sizes of the WORK and IWORK 00243 *> arrays, returns these values as the first entries of the WORK 00244 *> and IWORK arrays, and no error message related to LWORK or 00245 *> LIWORK is issued by XERBLA. 00246 *> \endverbatim 00247 *> 00248 *> \param[out] IWORK 00249 *> \verbatim 00250 *> IWORK is INTEGER array, dimension (MAX(1,LIWORK)) 00251 *> On exit, if INFO = 0, IWORK(1) returns the optimal (and 00252 *> minimal) LIWORK. 00253 *> \endverbatim 00254 *> 00255 *> \param[in] LIWORK 00256 *> \verbatim 00257 *> LIWORK is INTEGER 00258 *> The dimension of the array IWORK. LIWORK >= 10*N. 00259 *> 00260 *> If LIWORK = -1, then a workspace query is assumed; the 00261 *> routine only calculates the optimal sizes of the WORK and 00262 *> IWORK arrays, returns these values as the first entries of 00263 *> the WORK and IWORK arrays, and no error message related to 00264 *> LWORK or LIWORK is issued by XERBLA. 00265 *> \endverbatim 00266 *> 00267 *> \param[out] INFO 00268 *> \verbatim 00269 *> INFO is INTEGER 00270 *> = 0: successful exit 00271 *> < 0: if INFO = -i, the i-th argument had an illegal value 00272 *> > 0: Internal error 00273 *> \endverbatim 00274 * 00275 * Authors: 00276 * ======== 00277 * 00278 *> \author Univ. of Tennessee 00279 *> \author Univ. of California Berkeley 00280 *> \author Univ. of Colorado Denver 00281 *> \author NAG Ltd. 00282 * 00283 *> \date November 2011 00284 * 00285 *> \ingroup realOTHEReigen 00286 * 00287 *> \par Contributors: 00288 * ================== 00289 *> 00290 *> Inderjit Dhillon, IBM Almaden, USA \n 00291 *> Osni Marques, LBNL/NERSC, USA \n 00292 *> Ken Stanley, Computer Science Division, University of 00293 *> California at Berkeley, USA \n 00294 *> Jason Riedy, Computer Science Division, University of 00295 *> California at Berkeley, USA \n 00296 *> 00297 * ===================================================================== 00298 SUBROUTINE SSTEVR( JOBZ, RANGE, N, D, E, VL, VU, IL, IU, ABSTOL, 00299 $ M, W, Z, LDZ, ISUPPZ, WORK, LWORK, IWORK, 00300 $ LIWORK, INFO ) 00301 * 00302 * -- LAPACK driver routine (version 3.4.0) -- 00303 * -- LAPACK is a software package provided by Univ. of Tennessee, -- 00304 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- 00305 * November 2011 00306 * 00307 * .. Scalar Arguments .. 00308 CHARACTER JOBZ, RANGE 00309 INTEGER IL, INFO, IU, LDZ, LIWORK, LWORK, M, N 00310 REAL ABSTOL, VL, VU 00311 * .. 00312 * .. Array Arguments .. 00313 INTEGER ISUPPZ( * ), IWORK( * ) 00314 REAL D( * ), E( * ), W( * ), WORK( * ), Z( LDZ, * ) 00315 * .. 00316 * 00317 * ===================================================================== 00318 * 00319 * .. Parameters .. 00320 REAL ZERO, ONE, TWO 00321 PARAMETER ( ZERO = 0.0E+0, ONE = 1.0E+0, TWO = 2.0E+0 ) 00322 * .. 00323 * .. Local Scalars .. 00324 LOGICAL ALLEIG, INDEIG, TEST, LQUERY, VALEIG, WANTZ, 00325 $ TRYRAC 00326 CHARACTER ORDER 00327 INTEGER I, IEEEOK, IMAX, INDIBL, INDIFL, INDISP, 00328 $ INDIWO, ISCALE, J, JJ, LIWMIN, LWMIN, NSPLIT 00329 REAL BIGNUM, EPS, RMAX, RMIN, SAFMIN, SIGMA, SMLNUM, 00330 $ TMP1, TNRM, VLL, VUU 00331 * .. 00332 * .. External Functions .. 00333 LOGICAL LSAME 00334 INTEGER ILAENV 00335 REAL SLAMCH, SLANST 00336 EXTERNAL LSAME, ILAENV, SLAMCH, SLANST 00337 * .. 00338 * .. External Subroutines .. 00339 EXTERNAL SCOPY, SSCAL, SSTEBZ, SSTEMR, SSTEIN, SSTERF, 00340 $ SSWAP, XERBLA 00341 * .. 00342 * .. Intrinsic Functions .. 00343 INTRINSIC MAX, MIN, SQRT 00344 * .. 00345 * .. Executable Statements .. 00346 * 00347 * 00348 * Test the input parameters. 00349 * 00350 IEEEOK = ILAENV( 10, 'SSTEVR', 'N', 1, 2, 3, 4 ) 00351 * 00352 WANTZ = LSAME( JOBZ, 'V' ) 00353 ALLEIG = LSAME( RANGE, 'A' ) 00354 VALEIG = LSAME( RANGE, 'V' ) 00355 INDEIG = LSAME( RANGE, 'I' ) 00356 * 00357 LQUERY = ( ( LWORK.EQ.-1 ) .OR. ( LIWORK.EQ.-1 ) ) 00358 LWMIN = MAX( 1, 20*N ) 00359 LIWMIN = MAX(1, 10*N ) 00360 * 00361 * 00362 INFO = 0 00363 IF( .NOT.( WANTZ .OR. LSAME( JOBZ, 'N' ) ) ) THEN 00364 INFO = -1 00365 ELSE IF( .NOT.( ALLEIG .OR. VALEIG .OR. INDEIG ) ) THEN 00366 INFO = -2 00367 ELSE IF( N.LT.0 ) THEN 00368 INFO = -3 00369 ELSE 00370 IF( VALEIG ) THEN 00371 IF( N.GT.0 .AND. VU.LE.VL ) 00372 $ INFO = -7 00373 ELSE IF( INDEIG ) THEN 00374 IF( IL.LT.1 .OR. IL.GT.MAX( 1, N ) ) THEN 00375 INFO = -8 00376 ELSE IF( IU.LT.MIN( N, IL ) .OR. IU.GT.N ) THEN 00377 INFO = -9 00378 END IF 00379 END IF 00380 END IF 00381 IF( INFO.EQ.0 ) THEN 00382 IF( LDZ.LT.1 .OR. ( WANTZ .AND. LDZ.LT.N ) ) THEN 00383 INFO = -14 00384 END IF 00385 END IF 00386 * 00387 IF( INFO.EQ.0 ) THEN 00388 WORK( 1 ) = LWMIN 00389 IWORK( 1 ) = LIWMIN 00390 * 00391 IF( LWORK.LT.LWMIN .AND. .NOT.LQUERY ) THEN 00392 INFO = -17 00393 ELSE IF( LIWORK.LT.LIWMIN .AND. .NOT.LQUERY ) THEN 00394 INFO = -19 00395 END IF 00396 END IF 00397 * 00398 IF( INFO.NE.0 ) THEN 00399 CALL XERBLA( 'SSTEVR', -INFO ) 00400 RETURN 00401 ELSE IF( LQUERY ) THEN 00402 RETURN 00403 END IF 00404 * 00405 * Quick return if possible 00406 * 00407 M = 0 00408 IF( N.EQ.0 ) 00409 $ RETURN 00410 * 00411 IF( N.EQ.1 ) THEN 00412 IF( ALLEIG .OR. INDEIG ) THEN 00413 M = 1 00414 W( 1 ) = D( 1 ) 00415 ELSE 00416 IF( VL.LT.D( 1 ) .AND. VU.GE.D( 1 ) ) THEN 00417 M = 1 00418 W( 1 ) = D( 1 ) 00419 END IF 00420 END IF 00421 IF( WANTZ ) 00422 $ Z( 1, 1 ) = ONE 00423 RETURN 00424 END IF 00425 * 00426 * Get machine constants. 00427 * 00428 SAFMIN = SLAMCH( 'Safe minimum' ) 00429 EPS = SLAMCH( 'Precision' ) 00430 SMLNUM = SAFMIN / EPS 00431 BIGNUM = ONE / SMLNUM 00432 RMIN = SQRT( SMLNUM ) 00433 RMAX = MIN( SQRT( BIGNUM ), ONE / SQRT( SQRT( SAFMIN ) ) ) 00434 * 00435 * 00436 * Scale matrix to allowable range, if necessary. 00437 * 00438 ISCALE = 0 00439 VLL = VL 00440 VUU = VU 00441 * 00442 TNRM = SLANST( 'M', N, D, E ) 00443 IF( TNRM.GT.ZERO .AND. TNRM.LT.RMIN ) THEN 00444 ISCALE = 1 00445 SIGMA = RMIN / TNRM 00446 ELSE IF( TNRM.GT.RMAX ) THEN 00447 ISCALE = 1 00448 SIGMA = RMAX / TNRM 00449 END IF 00450 IF( ISCALE.EQ.1 ) THEN 00451 CALL SSCAL( N, SIGMA, D, 1 ) 00452 CALL SSCAL( N-1, SIGMA, E( 1 ), 1 ) 00453 IF( VALEIG ) THEN 00454 VLL = VL*SIGMA 00455 VUU = VU*SIGMA 00456 END IF 00457 END IF 00458 00459 * Initialize indices into workspaces. Note: These indices are used only 00460 * if SSTERF or SSTEMR fail. 00461 00462 * IWORK(INDIBL:INDIBL+M-1) corresponds to IBLOCK in SSTEBZ and 00463 * stores the block indices of each of the M<=N eigenvalues. 00464 INDIBL = 1 00465 * IWORK(INDISP:INDISP+NSPLIT-1) corresponds to ISPLIT in SSTEBZ and 00466 * stores the starting and finishing indices of each block. 00467 INDISP = INDIBL + N 00468 * IWORK(INDIFL:INDIFL+N-1) stores the indices of eigenvectors 00469 * that corresponding to eigenvectors that fail to converge in 00470 * SSTEIN. This information is discarded; if any fail, the driver 00471 * returns INFO > 0. 00472 INDIFL = INDISP + N 00473 * INDIWO is the offset of the remaining integer workspace. 00474 INDIWO = INDISP + N 00475 * 00476 * If all eigenvalues are desired, then 00477 * call SSTERF or SSTEMR. If this fails for some eigenvalue, then 00478 * try SSTEBZ. 00479 * 00480 * 00481 TEST = .FALSE. 00482 IF( INDEIG ) THEN 00483 IF( IL.EQ.1 .AND. IU.EQ.N ) THEN 00484 TEST = .TRUE. 00485 END IF 00486 END IF 00487 IF( ( ALLEIG .OR. TEST ) .AND. IEEEOK.EQ.1 ) THEN 00488 CALL SCOPY( N-1, E( 1 ), 1, WORK( 1 ), 1 ) 00489 IF( .NOT.WANTZ ) THEN 00490 CALL SCOPY( N, D, 1, W, 1 ) 00491 CALL SSTERF( N, W, WORK, INFO ) 00492 ELSE 00493 CALL SCOPY( N, D, 1, WORK( N+1 ), 1 ) 00494 IF (ABSTOL .LE. TWO*N*EPS) THEN 00495 TRYRAC = .TRUE. 00496 ELSE 00497 TRYRAC = .FALSE. 00498 END IF 00499 CALL SSTEMR( JOBZ, 'A', N, WORK( N+1 ), WORK, VL, VU, IL, 00500 $ IU, M, W, Z, LDZ, N, ISUPPZ, TRYRAC, 00501 $ WORK( 2*N+1 ), LWORK-2*N, IWORK, LIWORK, INFO ) 00502 * 00503 END IF 00504 IF( INFO.EQ.0 ) THEN 00505 M = N 00506 GO TO 10 00507 END IF 00508 INFO = 0 00509 END IF 00510 * 00511 * Otherwise, call SSTEBZ and, if eigenvectors are desired, SSTEIN. 00512 * 00513 IF( WANTZ ) THEN 00514 ORDER = 'B' 00515 ELSE 00516 ORDER = 'E' 00517 END IF 00518 00519 CALL SSTEBZ( RANGE, ORDER, N, VLL, VUU, IL, IU, ABSTOL, D, E, M, 00520 $ NSPLIT, W, IWORK( INDIBL ), IWORK( INDISP ), WORK, 00521 $ IWORK( INDIWO ), INFO ) 00522 * 00523 IF( WANTZ ) THEN 00524 CALL SSTEIN( N, D, E, M, W, IWORK( INDIBL ), IWORK( INDISP ), 00525 $ Z, LDZ, WORK, IWORK( INDIWO ), IWORK( INDIFL ), 00526 $ INFO ) 00527 END IF 00528 * 00529 * If matrix was scaled, then rescale eigenvalues appropriately. 00530 * 00531 10 CONTINUE 00532 IF( ISCALE.EQ.1 ) THEN 00533 IF( INFO.EQ.0 ) THEN 00534 IMAX = M 00535 ELSE 00536 IMAX = INFO - 1 00537 END IF 00538 CALL SSCAL( IMAX, ONE / SIGMA, W, 1 ) 00539 END IF 00540 * 00541 * If eigenvalues are not in order, then sort them, along with 00542 * eigenvectors. 00543 * 00544 IF( WANTZ ) THEN 00545 DO 30 J = 1, M - 1 00546 I = 0 00547 TMP1 = W( J ) 00548 DO 20 JJ = J + 1, M 00549 IF( W( JJ ).LT.TMP1 ) THEN 00550 I = JJ 00551 TMP1 = W( JJ ) 00552 END IF 00553 20 CONTINUE 00554 * 00555 IF( I.NE.0 ) THEN 00556 W( I ) = W( J ) 00557 W( J ) = TMP1 00558 CALL SSWAP( N, Z( 1, I ), 1, Z( 1, J ), 1 ) 00559 END IF 00560 30 CONTINUE 00561 END IF 00562 * 00563 * Causes problems with tests 19 & 20: 00564 * IF (wantz .and. INDEIG ) Z( 1,1) = Z(1,1) / 1.002 + .002 00565 * 00566 * 00567 WORK( 1 ) = LWMIN 00568 IWORK( 1 ) = LIWMIN 00569 RETURN 00570 * 00571 * End of SSTEVR 00572 * 00573 END