Annotation of rpl/lapack/lapack/dgeesx.f, revision 1.1
1.1 ! bertrand 1: SUBROUTINE DGEESX( JOBVS, SORT, SELECT, SENSE, N, A, LDA, SDIM,
! 2: $ WR, WI, VS, LDVS, RCONDE, RCONDV, WORK, LWORK,
! 3: $ IWORK, LIWORK, BWORK, INFO )
! 4: *
! 5: * -- LAPACK driver routine (version 3.2) --
! 6: * -- LAPACK is a software package provided by Univ. of Tennessee, --
! 7: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
! 8: * November 2006
! 9: *
! 10: * .. Scalar Arguments ..
! 11: CHARACTER JOBVS, SENSE, SORT
! 12: INTEGER INFO, LDA, LDVS, LIWORK, LWORK, N, SDIM
! 13: DOUBLE PRECISION RCONDE, RCONDV
! 14: * ..
! 15: * .. Array Arguments ..
! 16: LOGICAL BWORK( * )
! 17: INTEGER IWORK( * )
! 18: DOUBLE PRECISION A( LDA, * ), VS( LDVS, * ), WI( * ), WORK( * ),
! 19: $ WR( * )
! 20: * ..
! 21: * .. Function Arguments ..
! 22: LOGICAL SELECT
! 23: EXTERNAL SELECT
! 24: * ..
! 25: *
! 26: * Purpose
! 27: * =======
! 28: *
! 29: * DGEESX computes for an N-by-N real nonsymmetric matrix A, the
! 30: * eigenvalues, the real Schur form T, and, optionally, the matrix of
! 31: * Schur vectors Z. This gives the Schur factorization A = Z*T*(Z**T).
! 32: *
! 33: * Optionally, it also orders the eigenvalues on the diagonal of the
! 34: * real Schur form so that selected eigenvalues are at the top left;
! 35: * computes a reciprocal condition number for the average of the
! 36: * selected eigenvalues (RCONDE); and computes a reciprocal condition
! 37: * number for the right invariant subspace corresponding to the
! 38: * selected eigenvalues (RCONDV). The leading columns of Z form an
! 39: * orthonormal basis for this invariant subspace.
! 40: *
! 41: * For further explanation of the reciprocal condition numbers RCONDE
! 42: * and RCONDV, see Section 4.10 of the LAPACK Users' Guide (where
! 43: * these quantities are called s and sep respectively).
! 44: *
! 45: * A real matrix is in real Schur form if it is upper quasi-triangular
! 46: * with 1-by-1 and 2-by-2 blocks. 2-by-2 blocks will be standardized in
! 47: * the form
! 48: * [ a b ]
! 49: * [ c a ]
! 50: *
! 51: * where b*c < 0. The eigenvalues of such a block are a +- sqrt(bc).
! 52: *
! 53: * Arguments
! 54: * =========
! 55: *
! 56: * JOBVS (input) CHARACTER*1
! 57: * = 'N': Schur vectors are not computed;
! 58: * = 'V': Schur vectors are computed.
! 59: *
! 60: * SORT (input) CHARACTER*1
! 61: * Specifies whether or not to order the eigenvalues on the
! 62: * diagonal of the Schur form.
! 63: * = 'N': Eigenvalues are not ordered;
! 64: * = 'S': Eigenvalues are ordered (see SELECT).
! 65: *
! 66: * SELECT (external procedure) LOGICAL FUNCTION of two DOUBLE PRECISION arguments
! 67: * SELECT must be declared EXTERNAL in the calling subroutine.
! 68: * If SORT = 'S', SELECT is used to select eigenvalues to sort
! 69: * to the top left of the Schur form.
! 70: * If SORT = 'N', SELECT is not referenced.
! 71: * An eigenvalue WR(j)+sqrt(-1)*WI(j) is selected if
! 72: * SELECT(WR(j),WI(j)) is true; i.e., if either one of a
! 73: * complex conjugate pair of eigenvalues is selected, then both
! 74: * are. Note that a selected complex eigenvalue may no longer
! 75: * satisfy SELECT(WR(j),WI(j)) = .TRUE. after ordering, since
! 76: * ordering may change the value of complex eigenvalues
! 77: * (especially if the eigenvalue is ill-conditioned); in this
! 78: * case INFO may be set to N+3 (see INFO below).
! 79: *
! 80: * SENSE (input) CHARACTER*1
! 81: * Determines which reciprocal condition numbers are computed.
! 82: * = 'N': None are computed;
! 83: * = 'E': Computed for average of selected eigenvalues only;
! 84: * = 'V': Computed for selected right invariant subspace only;
! 85: * = 'B': Computed for both.
! 86: * If SENSE = 'E', 'V' or 'B', SORT must equal 'S'.
! 87: *
! 88: * N (input) INTEGER
! 89: * The order of the matrix A. N >= 0.
! 90: *
! 91: * A (input/output) DOUBLE PRECISION array, dimension (LDA, N)
! 92: * On entry, the N-by-N matrix A.
! 93: * On exit, A is overwritten by its real Schur form T.
! 94: *
! 95: * LDA (input) INTEGER
! 96: * The leading dimension of the array A. LDA >= max(1,N).
! 97: *
! 98: * SDIM (output) INTEGER
! 99: * If SORT = 'N', SDIM = 0.
! 100: * If SORT = 'S', SDIM = number of eigenvalues (after sorting)
! 101: * for which SELECT is true. (Complex conjugate
! 102: * pairs for which SELECT is true for either
! 103: * eigenvalue count as 2.)
! 104: *
! 105: * WR (output) DOUBLE PRECISION array, dimension (N)
! 106: * WI (output) DOUBLE PRECISION array, dimension (N)
! 107: * WR and WI contain the real and imaginary parts, respectively,
! 108: * of the computed eigenvalues, in the same order that they
! 109: * appear on the diagonal of the output Schur form T. Complex
! 110: * conjugate pairs of eigenvalues appear consecutively with the
! 111: * eigenvalue having the positive imaginary part first.
! 112: *
! 113: * VS (output) DOUBLE PRECISION array, dimension (LDVS,N)
! 114: * If JOBVS = 'V', VS contains the orthogonal matrix Z of Schur
! 115: * vectors.
! 116: * If JOBVS = 'N', VS is not referenced.
! 117: *
! 118: * LDVS (input) INTEGER
! 119: * The leading dimension of the array VS. LDVS >= 1, and if
! 120: * JOBVS = 'V', LDVS >= N.
! 121: *
! 122: * RCONDE (output) DOUBLE PRECISION
! 123: * If SENSE = 'E' or 'B', RCONDE contains the reciprocal
! 124: * condition number for the average of the selected eigenvalues.
! 125: * Not referenced if SENSE = 'N' or 'V'.
! 126: *
! 127: * RCONDV (output) DOUBLE PRECISION
! 128: * If SENSE = 'V' or 'B', RCONDV contains the reciprocal
! 129: * condition number for the selected right invariant subspace.
! 130: * Not referenced if SENSE = 'N' or 'E'.
! 131: *
! 132: * WORK (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK))
! 133: * On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
! 134: *
! 135: * LWORK (input) INTEGER
! 136: * The dimension of the array WORK. LWORK >= max(1,3*N).
! 137: * Also, if SENSE = 'E' or 'V' or 'B',
! 138: * LWORK >= N+2*SDIM*(N-SDIM), where SDIM is the number of
! 139: * selected eigenvalues computed by this routine. Note that
! 140: * N+2*SDIM*(N-SDIM) <= N+N*N/2. Note also that an error is only
! 141: * returned if LWORK < max(1,3*N), but if SENSE = 'E' or 'V' or
! 142: * 'B' this may not be large enough.
! 143: * For good performance, LWORK must generally be larger.
! 144: *
! 145: * If LWORK = -1, then a workspace query is assumed; the routine
! 146: * only calculates upper bounds on the optimal sizes of the
! 147: * arrays WORK and IWORK, returns these values as the first
! 148: * entries of the WORK and IWORK arrays, and no error messages
! 149: * related to LWORK or LIWORK are issued by XERBLA.
! 150: *
! 151: * IWORK (workspace/output) INTEGER array, dimension (MAX(1,LIWORK))
! 152: * On exit, if INFO = 0, IWORK(1) returns the optimal LIWORK.
! 153: *
! 154: * LIWORK (input) INTEGER
! 155: * The dimension of the array IWORK.
! 156: * LIWORK >= 1; if SENSE = 'V' or 'B', LIWORK >= SDIM*(N-SDIM).
! 157: * Note that SDIM*(N-SDIM) <= N*N/4. Note also that an error is
! 158: * only returned if LIWORK < 1, but if SENSE = 'V' or 'B' this
! 159: * may not be large enough.
! 160: *
! 161: * If LIWORK = -1, then a workspace query is assumed; the
! 162: * routine only calculates upper bounds on the optimal sizes of
! 163: * the arrays WORK and IWORK, returns these values as the first
! 164: * entries of the WORK and IWORK arrays, and no error messages
! 165: * related to LWORK or LIWORK are issued by XERBLA.
! 166: *
! 167: * BWORK (workspace) LOGICAL array, dimension (N)
! 168: * Not referenced if SORT = 'N'.
! 169: *
! 170: * INFO (output) INTEGER
! 171: * = 0: successful exit
! 172: * < 0: if INFO = -i, the i-th argument had an illegal value.
! 173: * > 0: if INFO = i, and i is
! 174: * <= N: the QR algorithm failed to compute all the
! 175: * eigenvalues; elements 1:ILO-1 and i+1:N of WR and WI
! 176: * contain those eigenvalues which have converged; if
! 177: * JOBVS = 'V', VS contains the transformation which
! 178: * reduces A to its partially converged Schur form.
! 179: * = N+1: the eigenvalues could not be reordered because some
! 180: * eigenvalues were too close to separate (the problem
! 181: * is very ill-conditioned);
! 182: * = N+2: after reordering, roundoff changed values of some
! 183: * complex eigenvalues so that leading eigenvalues in
! 184: * the Schur form no longer satisfy SELECT=.TRUE. This
! 185: * could also be caused by underflow due to scaling.
! 186: *
! 187: * =====================================================================
! 188: *
! 189: * .. Parameters ..
! 190: DOUBLE PRECISION ZERO, ONE
! 191: PARAMETER ( ZERO = 0.0D0, ONE = 1.0D0 )
! 192: * ..
! 193: * .. Local Scalars ..
! 194: LOGICAL CURSL, LASTSL, LQUERY, LST2SL, SCALEA, WANTSB,
! 195: $ WANTSE, WANTSN, WANTST, WANTSV, WANTVS
! 196: INTEGER HSWORK, I, I1, I2, IBAL, ICOND, IERR, IEVAL,
! 197: $ IHI, ILO, INXT, IP, ITAU, IWRK, LIWRK, LWRK,
! 198: $ MAXWRK, MINWRK
! 199: DOUBLE PRECISION ANRM, BIGNUM, CSCALE, EPS, SMLNUM
! 200: * ..
! 201: * .. Local Arrays ..
! 202: DOUBLE PRECISION DUM( 1 )
! 203: * ..
! 204: * .. External Subroutines ..
! 205: EXTERNAL DCOPY, DGEBAK, DGEBAL, DGEHRD, DHSEQR, DLACPY,
! 206: $ DLASCL, DORGHR, DSWAP, DTRSEN, XERBLA
! 207: * ..
! 208: * .. External Functions ..
! 209: LOGICAL LSAME
! 210: INTEGER ILAENV
! 211: DOUBLE PRECISION DLAMCH, DLANGE
! 212: EXTERNAL LSAME, ILAENV, DLABAD, DLAMCH, DLANGE
! 213: * ..
! 214: * .. Intrinsic Functions ..
! 215: INTRINSIC MAX, SQRT
! 216: * ..
! 217: * .. Executable Statements ..
! 218: *
! 219: * Test the input arguments
! 220: *
! 221: INFO = 0
! 222: WANTVS = LSAME( JOBVS, 'V' )
! 223: WANTST = LSAME( SORT, 'S' )
! 224: WANTSN = LSAME( SENSE, 'N' )
! 225: WANTSE = LSAME( SENSE, 'E' )
! 226: WANTSV = LSAME( SENSE, 'V' )
! 227: WANTSB = LSAME( SENSE, 'B' )
! 228: LQUERY = ( LWORK.EQ.-1 .OR. LIWORK.EQ.-1 )
! 229: IF( ( .NOT.WANTVS ) .AND. ( .NOT.LSAME( JOBVS, 'N' ) ) ) THEN
! 230: INFO = -1
! 231: ELSE IF( ( .NOT.WANTST ) .AND. ( .NOT.LSAME( SORT, 'N' ) ) ) THEN
! 232: INFO = -2
! 233: ELSE IF( .NOT.( WANTSN .OR. WANTSE .OR. WANTSV .OR. WANTSB ) .OR.
! 234: $ ( .NOT.WANTST .AND. .NOT.WANTSN ) ) THEN
! 235: INFO = -4
! 236: ELSE IF( N.LT.0 ) THEN
! 237: INFO = -5
! 238: ELSE IF( LDA.LT.MAX( 1, N ) ) THEN
! 239: INFO = -7
! 240: ELSE IF( LDVS.LT.1 .OR. ( WANTVS .AND. LDVS.LT.N ) ) THEN
! 241: INFO = -12
! 242: END IF
! 243: *
! 244: * Compute workspace
! 245: * (Note: Comments in the code beginning "RWorkspace:" describe the
! 246: * minimal amount of real workspace needed at that point in the
! 247: * code, as well as the preferred amount for good performance.
! 248: * IWorkspace refers to integer workspace.
! 249: * NB refers to the optimal block size for the immediately
! 250: * following subroutine, as returned by ILAENV.
! 251: * HSWORK refers to the workspace preferred by DHSEQR, as
! 252: * calculated below. HSWORK is computed assuming ILO=1 and IHI=N,
! 253: * the worst case.
! 254: * If SENSE = 'E', 'V' or 'B', then the amount of workspace needed
! 255: * depends on SDIM, which is computed by the routine DTRSEN later
! 256: * in the code.)
! 257: *
! 258: IF( INFO.EQ.0 ) THEN
! 259: LIWRK = 1
! 260: IF( N.EQ.0 ) THEN
! 261: MINWRK = 1
! 262: LWRK = 1
! 263: ELSE
! 264: MAXWRK = 2*N + N*ILAENV( 1, 'DGEHRD', ' ', N, 1, N, 0 )
! 265: MINWRK = 3*N
! 266: *
! 267: CALL DHSEQR( 'S', JOBVS, N, 1, N, A, LDA, WR, WI, VS, LDVS,
! 268: $ WORK, -1, IEVAL )
! 269: HSWORK = WORK( 1 )
! 270: *
! 271: IF( .NOT.WANTVS ) THEN
! 272: MAXWRK = MAX( MAXWRK, N + HSWORK )
! 273: ELSE
! 274: MAXWRK = MAX( MAXWRK, 2*N + ( N - 1 )*ILAENV( 1,
! 275: $ 'DORGHR', ' ', N, 1, N, -1 ) )
! 276: MAXWRK = MAX( MAXWRK, N + HSWORK )
! 277: END IF
! 278: LWRK = MAXWRK
! 279: IF( .NOT.WANTSN )
! 280: $ LWRK = MAX( LWRK, N + ( N*N )/2 )
! 281: IF( WANTSV .OR. WANTSB )
! 282: $ LIWRK = ( N*N )/4
! 283: END IF
! 284: IWORK( 1 ) = LIWRK
! 285: WORK( 1 ) = LWRK
! 286: *
! 287: IF( LWORK.LT.MINWRK .AND. .NOT.LQUERY ) THEN
! 288: INFO = -16
! 289: ELSE IF( LIWORK.LT.1 .AND. .NOT.LQUERY ) THEN
! 290: INFO = -18
! 291: END IF
! 292: END IF
! 293: *
! 294: IF( INFO.NE.0 ) THEN
! 295: CALL XERBLA( 'DGEESX', -INFO )
! 296: RETURN
! 297: END IF
! 298: *
! 299: * Quick return if possible
! 300: *
! 301: IF( N.EQ.0 ) THEN
! 302: SDIM = 0
! 303: RETURN
! 304: END IF
! 305: *
! 306: * Get machine constants
! 307: *
! 308: EPS = DLAMCH( 'P' )
! 309: SMLNUM = DLAMCH( 'S' )
! 310: BIGNUM = ONE / SMLNUM
! 311: CALL DLABAD( SMLNUM, BIGNUM )
! 312: SMLNUM = SQRT( SMLNUM ) / EPS
! 313: BIGNUM = ONE / SMLNUM
! 314: *
! 315: * Scale A if max element outside range [SMLNUM,BIGNUM]
! 316: *
! 317: ANRM = DLANGE( 'M', N, N, A, LDA, DUM )
! 318: SCALEA = .FALSE.
! 319: IF( ANRM.GT.ZERO .AND. ANRM.LT.SMLNUM ) THEN
! 320: SCALEA = .TRUE.
! 321: CSCALE = SMLNUM
! 322: ELSE IF( ANRM.GT.BIGNUM ) THEN
! 323: SCALEA = .TRUE.
! 324: CSCALE = BIGNUM
! 325: END IF
! 326: IF( SCALEA )
! 327: $ CALL DLASCL( 'G', 0, 0, ANRM, CSCALE, N, N, A, LDA, IERR )
! 328: *
! 329: * Permute the matrix to make it more nearly triangular
! 330: * (RWorkspace: need N)
! 331: *
! 332: IBAL = 1
! 333: CALL DGEBAL( 'P', N, A, LDA, ILO, IHI, WORK( IBAL ), IERR )
! 334: *
! 335: * Reduce to upper Hessenberg form
! 336: * (RWorkspace: need 3*N, prefer 2*N+N*NB)
! 337: *
! 338: ITAU = N + IBAL
! 339: IWRK = N + ITAU
! 340: CALL DGEHRD( N, ILO, IHI, A, LDA, WORK( ITAU ), WORK( IWRK ),
! 341: $ LWORK-IWRK+1, IERR )
! 342: *
! 343: IF( WANTVS ) THEN
! 344: *
! 345: * Copy Householder vectors to VS
! 346: *
! 347: CALL DLACPY( 'L', N, N, A, LDA, VS, LDVS )
! 348: *
! 349: * Generate orthogonal matrix in VS
! 350: * (RWorkspace: need 3*N-1, prefer 2*N+(N-1)*NB)
! 351: *
! 352: CALL DORGHR( N, ILO, IHI, VS, LDVS, WORK( ITAU ), WORK( IWRK ),
! 353: $ LWORK-IWRK+1, IERR )
! 354: END IF
! 355: *
! 356: SDIM = 0
! 357: *
! 358: * Perform QR iteration, accumulating Schur vectors in VS if desired
! 359: * (RWorkspace: need N+1, prefer N+HSWORK (see comments) )
! 360: *
! 361: IWRK = ITAU
! 362: CALL DHSEQR( 'S', JOBVS, N, ILO, IHI, A, LDA, WR, WI, VS, LDVS,
! 363: $ WORK( IWRK ), LWORK-IWRK+1, IEVAL )
! 364: IF( IEVAL.GT.0 )
! 365: $ INFO = IEVAL
! 366: *
! 367: * Sort eigenvalues if desired
! 368: *
! 369: IF( WANTST .AND. INFO.EQ.0 ) THEN
! 370: IF( SCALEA ) THEN
! 371: CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WR, N, IERR )
! 372: CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N, 1, WI, N, IERR )
! 373: END IF
! 374: DO 10 I = 1, N
! 375: BWORK( I ) = SELECT( WR( I ), WI( I ) )
! 376: 10 CONTINUE
! 377: *
! 378: * Reorder eigenvalues, transform Schur vectors, and compute
! 379: * reciprocal condition numbers
! 380: * (RWorkspace: if SENSE is not 'N', need N+2*SDIM*(N-SDIM)
! 381: * otherwise, need N )
! 382: * (IWorkspace: if SENSE is 'V' or 'B', need SDIM*(N-SDIM)
! 383: * otherwise, need 0 )
! 384: *
! 385: CALL DTRSEN( SENSE, JOBVS, BWORK, N, A, LDA, VS, LDVS, WR, WI,
! 386: $ SDIM, RCONDE, RCONDV, WORK( IWRK ), LWORK-IWRK+1,
! 387: $ IWORK, LIWORK, ICOND )
! 388: IF( .NOT.WANTSN )
! 389: $ MAXWRK = MAX( MAXWRK, N+2*SDIM*( N-SDIM ) )
! 390: IF( ICOND.EQ.-15 ) THEN
! 391: *
! 392: * Not enough real workspace
! 393: *
! 394: INFO = -16
! 395: ELSE IF( ICOND.EQ.-17 ) THEN
! 396: *
! 397: * Not enough integer workspace
! 398: *
! 399: INFO = -18
! 400: ELSE IF( ICOND.GT.0 ) THEN
! 401: *
! 402: * DTRSEN failed to reorder or to restore standard Schur form
! 403: *
! 404: INFO = ICOND + N
! 405: END IF
! 406: END IF
! 407: *
! 408: IF( WANTVS ) THEN
! 409: *
! 410: * Undo balancing
! 411: * (RWorkspace: need N)
! 412: *
! 413: CALL DGEBAK( 'P', 'R', N, ILO, IHI, WORK( IBAL ), N, VS, LDVS,
! 414: $ IERR )
! 415: END IF
! 416: *
! 417: IF( SCALEA ) THEN
! 418: *
! 419: * Undo scaling for the Schur form of A
! 420: *
! 421: CALL DLASCL( 'H', 0, 0, CSCALE, ANRM, N, N, A, LDA, IERR )
! 422: CALL DCOPY( N, A, LDA+1, WR, 1 )
! 423: IF( ( WANTSV .OR. WANTSB ) .AND. INFO.EQ.0 ) THEN
! 424: DUM( 1 ) = RCONDV
! 425: CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, 1, 1, DUM, 1, IERR )
! 426: RCONDV = DUM( 1 )
! 427: END IF
! 428: IF( CSCALE.EQ.SMLNUM ) THEN
! 429: *
! 430: * If scaling back towards underflow, adjust WI if an
! 431: * offdiagonal element of a 2-by-2 block in the Schur form
! 432: * underflows.
! 433: *
! 434: IF( IEVAL.GT.0 ) THEN
! 435: I1 = IEVAL + 1
! 436: I2 = IHI - 1
! 437: CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, ILO-1, 1, WI, N,
! 438: $ IERR )
! 439: ELSE IF( WANTST ) THEN
! 440: I1 = 1
! 441: I2 = N - 1
! 442: ELSE
! 443: I1 = ILO
! 444: I2 = IHI - 1
! 445: END IF
! 446: INXT = I1 - 1
! 447: DO 20 I = I1, I2
! 448: IF( I.LT.INXT )
! 449: $ GO TO 20
! 450: IF( WI( I ).EQ.ZERO ) THEN
! 451: INXT = I + 1
! 452: ELSE
! 453: IF( A( I+1, I ).EQ.ZERO ) THEN
! 454: WI( I ) = ZERO
! 455: WI( I+1 ) = ZERO
! 456: ELSE IF( A( I+1, I ).NE.ZERO .AND. A( I, I+1 ).EQ.
! 457: $ ZERO ) THEN
! 458: WI( I ) = ZERO
! 459: WI( I+1 ) = ZERO
! 460: IF( I.GT.1 )
! 461: $ CALL DSWAP( I-1, A( 1, I ), 1, A( 1, I+1 ), 1 )
! 462: IF( N.GT.I+1 )
! 463: $ CALL DSWAP( N-I-1, A( I, I+2 ), LDA,
! 464: $ A( I+1, I+2 ), LDA )
! 465: CALL DSWAP( N, VS( 1, I ), 1, VS( 1, I+1 ), 1 )
! 466: A( I, I+1 ) = A( I+1, I )
! 467: A( I+1, I ) = ZERO
! 468: END IF
! 469: INXT = I + 2
! 470: END IF
! 471: 20 CONTINUE
! 472: END IF
! 473: CALL DLASCL( 'G', 0, 0, CSCALE, ANRM, N-IEVAL, 1,
! 474: $ WI( IEVAL+1 ), MAX( N-IEVAL, 1 ), IERR )
! 475: END IF
! 476: *
! 477: IF( WANTST .AND. INFO.EQ.0 ) THEN
! 478: *
! 479: * Check if reordering successful
! 480: *
! 481: LASTSL = .TRUE.
! 482: LST2SL = .TRUE.
! 483: SDIM = 0
! 484: IP = 0
! 485: DO 30 I = 1, N
! 486: CURSL = SELECT( WR( I ), WI( I ) )
! 487: IF( WI( I ).EQ.ZERO ) THEN
! 488: IF( CURSL )
! 489: $ SDIM = SDIM + 1
! 490: IP = 0
! 491: IF( CURSL .AND. .NOT.LASTSL )
! 492: $ INFO = N + 2
! 493: ELSE
! 494: IF( IP.EQ.1 ) THEN
! 495: *
! 496: * Last eigenvalue of conjugate pair
! 497: *
! 498: CURSL = CURSL .OR. LASTSL
! 499: LASTSL = CURSL
! 500: IF( CURSL )
! 501: $ SDIM = SDIM + 2
! 502: IP = -1
! 503: IF( CURSL .AND. .NOT.LST2SL )
! 504: $ INFO = N + 2
! 505: ELSE
! 506: *
! 507: * First eigenvalue of conjugate pair
! 508: *
! 509: IP = 1
! 510: END IF
! 511: END IF
! 512: LST2SL = LASTSL
! 513: LASTSL = CURSL
! 514: 30 CONTINUE
! 515: END IF
! 516: *
! 517: WORK( 1 ) = MAXWRK
! 518: IF( WANTSV .OR. WANTSB ) THEN
! 519: IWORK( 1 ) = MAX( 1, SDIM*( N-SDIM ) )
! 520: ELSE
! 521: IWORK( 1 ) = 1
! 522: END IF
! 523: *
! 524: RETURN
! 525: *
! 526: * End of DGEESX
! 527: *
! 528: END
CVSweb interface <joel.bertrand@systella.fr>
![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to dgeesx.f CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [local] / rpl / lapack / lapack