1 /* ../netlib/dtgsna.f -- translated by f2c (version 20100827). You must link the resulting object file with libf2c: on Microsoft Windows system, link with libf2c.lib;
2 on Linux or Unix systems, link with .../path/to/libf2c.a -lm or, if you install libf2c.a in a standard place, with -lf2c -lm -- in that order, at the end of the command line, as in cc *.o -lf2c -lm Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., http://www.netlib.org/f2c/libf2c.zip */
3 #include "FLA_f2c.h" /* Table of constant values */
4 static integer c__1 = 1;
5 static doublereal c_b19 = 1.;
6 static doublereal c_b21 = 0.;
7 static integer c__2 = 2;
8 static logical c_false = FALSE_;
9 static integer c__3 = 3;
10 /* > \brief \b DTGSNA */
11 /* =========== DOCUMENTATION =========== */
12 /* Online html documentation available at */
13 /* http://www.netlib.org/lapack/explore-html/ */
14 /* > \htmlonly */
15 /* > Download DTGSNA + dependencies */
16 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dtgsna. f"> */
17 /* > [TGZ]</a> */
18 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dtgsna. f"> */
19 /* > [ZIP]</a> */
20 /* > <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dtgsna. f"> */
21 /* > [TXT]</a> */
22 /* > \endhtmlonly */
23 /* Definition: */
24 /* =========== */
25 /* SUBROUTINE DTGSNA( JOB, HOWMNY, SELECT, N, A, LDA, B, LDB, VL, */
26 /* LDVL, VR, LDVR, S, DIF, MM, M, WORK, LWORK, */
27 /* IWORK, INFO ) */
28 /* .. Scalar Arguments .. */
29 /* CHARACTER HOWMNY, JOB */
30 /* INTEGER INFO, LDA, LDB, LDVL, LDVR, LWORK, M, MM, N */
31 /* .. */
32 /* .. Array Arguments .. */
33 /* LOGICAL SELECT( * ) */
34 /* INTEGER IWORK( * ) */
35 /* DOUBLE PRECISION A( LDA, * ), B( LDB, * ), DIF( * ), S( * ), */
36 /* $ VL( LDVL, * ), VR( LDVR, * ), WORK( * ) */
37 /* .. */
38 /* > \par Purpose: */
39 /* ============= */
40 /* > */
41 /* > \verbatim */
42 /* > */
43 /* > DTGSNA estimates reciprocal condition numbers for specified */
44 /* > eigenvalues and/or eigenvectors of a matrix pair (A, B) in */
45 /* > generalized real Schur canonical form (or of any matrix pair */
46 /* > (Q*A*Z**T, Q*B*Z**T) with orthogonal matrices Q and Z, where */
47 /* > Z**T denotes the transpose of Z. */
48 /* > */
49 /* > (A, B) must be in generalized real Schur form (as returned by DGGES), */
50 /* > i.e. A is block upper triangular with 1-by-1 and 2-by-2 diagonal */
51 /* > blocks. B is upper triangular. */
52 /* > */
53 /* > \endverbatim */
54 /* Arguments: */
55 /* ========== */
56 /* > \param[in] JOB */
57 /* > \verbatim */
58 /* > JOB is CHARACTER*1 */
59 /* > Specifies whether condition numbers are required for */
60 /* > eigenvalues (S) or eigenvectors (DIF): */
61 /* > = 'E': for eigenvalues only (S);
62 */
63 /* > = 'V': for eigenvectors only (DIF);
64 */
65 /* > = 'B': for both eigenvalues and eigenvectors (S and DIF). */
66 /* > \endverbatim */
67 /* > */
68 /* > \param[in] HOWMNY */
69 /* > \verbatim */
70 /* > HOWMNY is CHARACTER*1 */
71 /* > = 'A': compute condition numbers for all eigenpairs;
72 */
73 /* > = 'S': compute condition numbers for selected eigenpairs */
74 /* > specified by the array SELECT. */
75 /* > \endverbatim */
76 /* > */
77 /* > \param[in] SELECT */
78 /* > \verbatim */
79 /* > SELECT is LOGICAL array, dimension (N) */
80 /* > If HOWMNY = 'S', SELECT specifies the eigenpairs for which */
81 /* > condition numbers are required. To select condition numbers */
82 /* > for the eigenpair corresponding to a real eigenvalue w(j), */
83 /* > SELECT(j) must be set to .TRUE.. To select condition numbers */
84 /* > corresponding to a complex conjugate pair of eigenvalues w(j) */
85 /* > and w(j+1), either SELECT(j) or SELECT(j+1) or both, must be */
86 /* > set to .TRUE.. */
87 /* > If HOWMNY = 'A', SELECT is not referenced. */
88 /* > \endverbatim */
89 /* > */
90 /* > \param[in] N */
91 /* > \verbatim */
92 /* > N is INTEGER */
93 /* > The order of the square matrix pair (A, B). N >= 0. */
94 /* > \endverbatim */
95 /* > */
96 /* > \param[in] A */
97 /* > \verbatim */
98 /* > A is DOUBLE PRECISION array, dimension (LDA,N) */
99 /* > The upper quasi-triangular matrix A in the pair (A,B). */
100 /* > \endverbatim */
101 /* > */
102 /* > \param[in] LDA */
103 /* > \verbatim */
104 /* > LDA is INTEGER */
105 /* > The leading dimension of the array A. LDA >= max(1,N). */
106 /* > \endverbatim */
107 /* > */
108 /* > \param[in] B */
109 /* > \verbatim */
110 /* > B is DOUBLE PRECISION array, dimension (LDB,N) */
111 /* > The upper triangular matrix B in the pair (A,B). */
112 /* > \endverbatim */
113 /* > */
114 /* > \param[in] LDB */
115 /* > \verbatim */
116 /* > LDB is INTEGER */
117 /* > The leading dimension of the array B. LDB >= max(1,N). */
118 /* > \endverbatim */
119 /* > */
120 /* > \param[in] VL */
121 /* > \verbatim */
122 /* > VL is DOUBLE PRECISION array, dimension (LDVL,M) */
123 /* > If JOB = 'E' or 'B', VL must contain left eigenvectors of */
124 /* > (A, B), corresponding to the eigenpairs specified by HOWMNY */
125 /* > and SELECT. The eigenvectors must be stored in consecutive */
126 /* > columns of VL, as returned by DTGEVC. */
127 /* > If JOB = 'V', VL is not referenced. */
128 /* > \endverbatim */
129 /* > */
130 /* > \param[in] LDVL */
131 /* > \verbatim */
132 /* > LDVL is INTEGER */
133 /* > The leading dimension of the array VL. LDVL >= 1. */
134 /* > If JOB = 'E' or 'B', LDVL >= N. */
135 /* > \endverbatim */
136 /* > */
137 /* > \param[in] VR */
138 /* > \verbatim */
139 /* > VR is DOUBLE PRECISION array, dimension (LDVR,M) */
140 /* > If JOB = 'E' or 'B', VR must contain right eigenvectors of */
141 /* > (A, B), corresponding to the eigenpairs specified by HOWMNY */
142 /* > and SELECT. The eigenvectors must be stored in consecutive */
143 /* > columns ov VR, as returned by DTGEVC. */
144 /* > If JOB = 'V', VR is not referenced. */
145 /* > \endverbatim */
146 /* > */
147 /* > \param[in] LDVR */
148 /* > \verbatim */
149 /* > LDVR is INTEGER */
150 /* > The leading dimension of the array VR. LDVR >= 1. */
151 /* > If JOB = 'E' or 'B', LDVR >= N. */
152 /* > \endverbatim */
153 /* > */
154 /* > \param[out] S */
155 /* > \verbatim */
156 /* > S is DOUBLE PRECISION array, dimension (MM) */
157 /* > If JOB = 'E' or 'B', the reciprocal condition numbers of the */
158 /* > selected eigenvalues, stored in consecutive elements of the */
159 /* > array. For a complex conjugate pair of eigenvalues two */
160 /* > consecutive elements of S are set to the same value. Thus */
161 /* > S(j), DIF(j), and the j-th columns of VL and VR all */
162 /* > correspond to the same eigenpair (but not in general the */
163 /* > j-th eigenpair, unless all eigenpairs are selected). */
164 /* > If JOB = 'V', S is not referenced. */
165 /* > \endverbatim */
166 /* > */
167 /* > \param[out] DIF */
168 /* > \verbatim */
169 /* > DIF is DOUBLE PRECISION array, dimension (MM) */
170 /* > If JOB = 'V' or 'B', the estimated reciprocal condition */
171 /* > numbers of the selected eigenvectors, stored in consecutive */
172 /* > elements of the array. For a complex eigenvector two */
173 /* > consecutive elements of DIF are set to the same value. If */
174 /* > the eigenvalues cannot be reordered to compute DIF(j), DIF(j) */
175 /* > is set to 0;
176 this can only occur when the true value would be */
177 /* > very small anyway. */
178 /* > If JOB = 'E', DIF is not referenced. */
179 /* > \endverbatim */
180 /* > */
181 /* > \param[in] MM */
182 /* > \verbatim */
183 /* > MM is INTEGER */
184 /* > The number of elements in the arrays S and DIF. MM >= M. */
185 /* > \endverbatim */
186 /* > */
187 /* > \param[out] M */
188 /* > \verbatim */
189 /* > M is INTEGER */
190 /* > The number of elements of the arrays S and DIF used to store */
191 /* > the specified condition numbers;
192 for each selected real */
193 /* > eigenvalue one element is used, and for each selected complex */
194 /* > conjugate pair of eigenvalues, two elements are used. */
195 /* > If HOWMNY = 'A', M is set to N. */
196 /* > \endverbatim */
197 /* > */
198 /* > \param[out] WORK */
199 /* > \verbatim */
200 /* > WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) */
201 /* > On exit, if INFO = 0, WORK(1) returns the optimal LWORK. */
202 /* > \endverbatim */
203 /* > */
204 /* > \param[in] LWORK */
205 /* > \verbatim */
206 /* > LWORK is INTEGER */
207 /* > The dimension of the array WORK. LWORK >= max(1,N). */
208 /* > If JOB = 'V' or 'B' LWORK >= 2*N*(N+2)+16. */
209 /* > */
210 /* > If LWORK = -1, then a workspace query is assumed;
211 the routine */
212 /* > only calculates the optimal size of the WORK array, returns */
213 /* > this value as the first entry of the WORK array, and no error */
214 /* > message related to LWORK is issued by XERBLA. */
215 /* > \endverbatim */
216 /* > */
217 /* > \param[out] IWORK */
218 /* > \verbatim */
219 /* > IWORK is INTEGER array, dimension (N + 6) */
220 /* > If JOB = 'E', IWORK is not referenced. */
221 /* > \endverbatim */
222 /* > */
223 /* > \param[out] INFO */
224 /* > \verbatim */
225 /* > INFO is INTEGER */
226 /* > =0: Successful exit */
227 /* > <0: If INFO = -i, the i-th argument had an illegal value */
228 /* > \endverbatim */
229 /* Authors: */
230 /* ======== */
231 /* > \author Univ. of Tennessee */
232 /* > \author Univ. of California Berkeley */
233 /* > \author Univ. of Colorado Denver */
234 /* > \author NAG Ltd. */
235 /* > \date November 2011 */
236 /* > \ingroup doubleOTHERcomputational */
237 /* > \par Further Details: */
238 /* ===================== */
239 /* > */
240 /* > \verbatim */
241 /* > */
242 /* > The reciprocal of the condition number of a generalized eigenvalue */
243 /* > w = (a, b) is defined as */
244 /* > */
245 /* > S(w) = (|u**TAv|**2 + |u**TBv|**2)**(1/2) / (norm(u)*norm(v)) */
246 /* > */
247 /* > where u and v are the left and right eigenvectors of (A, B) */
248 /* > corresponding to w;
249 |z| denotes the absolute value of the complex */
250 /* > number, and norm(u) denotes the 2-norm of the vector u. */
251 /* > The pair (a, b) corresponds to an eigenvalue w = a/b (= u**TAv/u**TBv) */
252 /* > of the matrix pair (A, B). If both a and b equal zero, then (A B) is */
253 /* > singular and S(I) = -1 is returned. */
254 /* > */
255 /* > An approximate error bound on the chordal distance between the i-th */
256 /* > computed generalized eigenvalue w and the corresponding exact */
257 /* > eigenvalue lambda is */
258 /* > */
259 /* > chord(w, lambda) <= EPS * norm(A, B) / S(I) */
260 /* > */
261 /* > where EPS is the machine precision. */
262 /* > */
263 /* > The reciprocal of the condition number DIF(i) of right eigenvector u */
264 /* > and left eigenvector v corresponding to the generalized eigenvalue w */
265 /* > is defined as follows: */
266 /* > */
267 /* > a) If the i-th eigenvalue w = (a,b) is real */
268 /* > */
269 /* > Suppose U and V are orthogonal transformations such that */
270 /* > */
271 /* > U**T*(A, B)*V = (S, T) = ( a * ) ( b * ) 1 */
272 /* > ( 0 S22 ),( 0 T22 ) n-1 */
273 /* > 1 n-1 1 n-1 */
274 /* > */
275 /* > Then the reciprocal condition number DIF(i) is */
276 /* > */
277 /* > Difl((a, b), (S22, T22)) = sigma-min( Zl ), */
278 /* > */
279 /* > where sigma-min(Zl) denotes the smallest singular value of the */
280 /* > 2(n-1)-by-2(n-1) matrix */
281 /* > */
282 /* > Zl = [ kron(a, In-1) -kron(1, S22) ] */
283 /* > [ kron(b, In-1) -kron(1, T22) ] . */
284 /* > */
285 /* > Here In-1 is the identity matrix of size n-1. kron(X, Y) is the */
286 /* > Kronecker product between the matrices X and Y. */
287 /* > */
288 /* > Note that if the default method for computing DIF(i) is wanted */
289 /* > (see DLATDF), then the parameter DIFDRI (see below) should be */
290 /* > changed from 3 to 4 (routine DLATDF(IJOB = 2 will be used)). */
291 /* > See DTGSYL for more details. */
292 /* > */
293 /* > b) If the i-th and (i+1)-th eigenvalues are complex conjugate pair, */
294 /* > */
295 /* > Suppose U and V are orthogonal transformations such that */
296 /* > */
297 /* > U**T*(A, B)*V = (S, T) = ( S11 * ) ( T11 * ) 2 */
298 /* > ( 0 S22 ),( 0 T22) n-2 */
299 /* > 2 n-2 2 n-2 */
300 /* > */
301 /* > and (S11, T11) corresponds to the complex conjugate eigenvalue */
302 /* > pair (w, conjg(w)). There exist unitary matrices U1 and V1 such */
303 /* > that */
304 /* > */
305 /* > U1**T*S11*V1 = ( s11 s12 ) and U1**T*T11*V1 = ( t11 t12 ) */
306 /* > ( 0 s22 ) ( 0 t22 ) */
307 /* > */
308 /* > where the generalized eigenvalues w = s11/t11 and */
309 /* > conjg(w) = s22/t22. */
310 /* > */
311 /* > Then the reciprocal condition number DIF(i) is bounded by */
312 /* > */
313 /* > min( d1, max( 1, |real(s11)/real(s22)| )*d2 ) */
314 /* > */
315 /* > where, d1 = Difl((s11, t11), (s22, t22)) = sigma-min(Z1), where */
316 /* > Z1 is the complex 2-by-2 matrix */
317 /* > */
318 /* > Z1 = [ s11 -s22 ] */
319 /* > [ t11 -t22 ], */
320 /* > */
321 /* > This is done by computing (using real arithmetic) the */
322 /* > roots of the characteristical polynomial det(Z1**T * Z1 - lambda I), */
323 /* > where Z1**T denotes the transpose of Z1 and det(X) denotes */
324 /* > the determinant of X. */
325 /* > */
326 /* > and d2 is an upper bound on Difl((S11, T11), (S22, T22)), i.e. an */
327 /* > upper bound on sigma-min(Z2), where Z2 is (2n-2)-by-(2n-2) */
328 /* > */
329 /* > Z2 = [ kron(S11**T, In-2) -kron(I2, S22) ] */
330 /* > [ kron(T11**T, In-2) -kron(I2, T22) ] */
331 /* > */
332 /* > Note that if the default method for computing DIF is wanted (see */
333 /* > DLATDF), then the parameter DIFDRI (see below) should be changed */
334 /* > from 3 to 4 (routine DLATDF(IJOB = 2 will be used)). See DTGSYL */
335 /* > for more details. */
336 /* > */
337 /* > For each eigenvalue/vector specified by SELECT, DIF stores a */
338 /* > Frobenius norm-based estimate of Difl. */
339 /* > */
340 /* > An approximate error bound for the i-th computed eigenvector VL(i) or */
341 /* > VR(i) is given by */
342 /* > */
343 /* > EPS * norm(A, B) / DIF(i). */
344 /* > */
345 /* > See ref. [2-3] for more details and further references. */
346 /* > \endverbatim */
347 /* > \par Contributors: */
348 /* ================== */
349 /* > */
350 /* > Bo Kagstrom and Peter Poromaa, Department of Computing Science, */
351 /* > Umea University, S-901 87 Umea, Sweden. */
352 /* > \par References: */
353 /* ================ */
354 /* > */
355 /* > \verbatim */
356 /* > */
357 /* > [1] B. Kagstrom;
358 A Direct Method for Reordering Eigenvalues in the */
359 /* > Generalized Real Schur Form of a Regular Matrix Pair (A, B), in */
360 /* > M.S. Moonen et al (eds), Linear Algebra for Large Scale and */
361 /* > Real-Time Applications, Kluwer Academic Publ. 1993, pp 195-218. */
362 /* > */
363 /* > [2] B. Kagstrom and P. Poromaa;
364 Computing Eigenspaces with Specified */
365 /* > Eigenvalues of a Regular Matrix Pair (A, B) and Condition */
366 /* > Estimation: Theory, Algorithms and Software, */
367 /* > Report UMINF - 94.04, Department of Computing Science, Umea */
368 /* > University, S-901 87 Umea, Sweden, 1994. Also as LAPACK Working */
369 /* > Note 87. To appear in Numerical Algorithms, 1996. */
370 /* > */
371 /* > [3] B. Kagstrom and P. Poromaa, LAPACK-Style Algorithms and Software */
372 /* > for Solving the Generalized Sylvester Equation and Estimating the */
373 /* > Separation between Regular Matrix Pairs, Report UMINF - 93.23, */
374 /* > Department of Computing Science, Umea University, S-901 87 Umea, */
375 /* > Sweden, December 1993, Revised April 1994, Also as LAPACK Working */
376 /* > Note 75. To appear in ACM Trans. on Math. Software, Vol 22, */
377 /* > No 1, 1996. */
378 /* > \endverbatim */
379 /* > */
380 /* ===================================================================== */
381 /* Subroutine */
dtgsna_(char * job,char * howmny,logical * select,integer * n,doublereal * a,integer * lda,doublereal * b,integer * ldb,doublereal * vl,integer * ldvl,doublereal * vr,integer * ldvr,doublereal * s,doublereal * dif,integer * mm,integer * m,doublereal * work,integer * lwork,integer * iwork,integer * info)382 int dtgsna_(char *job, char *howmny, logical *select, integer *n, doublereal *a, integer *lda, doublereal *b, integer *ldb, doublereal *vl, integer *ldvl, doublereal *vr, integer *ldvr, doublereal *s, doublereal *dif, integer *mm, integer *m, doublereal * work, integer *lwork, integer *iwork, integer *info)
383 {
384 /* System generated locals */
385 integer a_dim1, a_offset, b_dim1, b_offset, vl_dim1, vl_offset, vr_dim1, vr_offset, i__1, i__2;
386 doublereal d__1, d__2;
387 /* Builtin functions */
388 double sqrt(doublereal);
389 /* Local variables */
390 integer i__, k;
391 doublereal c1, c2;
392 integer n1, n2, ks, iz;
393 doublereal eps, beta, cond;
394 extern doublereal ddot_(integer *, doublereal *, integer *, doublereal *, integer *);
395 logical pair;
396 integer ierr;
397 doublereal uhav, uhbv;
398 integer ifst;
399 doublereal lnrm;
400 integer ilst;
401 doublereal rnrm;
402 extern /* Subroutine */
403 int dlag2_(doublereal *, integer *, doublereal *, integer *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *, doublereal *);
404 extern doublereal dnrm2_(integer *, doublereal *, integer *);
405 doublereal root1, root2, scale;
406 extern logical lsame_(char *, char *);
407 extern /* Subroutine */
408 int dgemv_(char *, integer *, integer *, doublereal *, doublereal *, integer *, doublereal *, integer *, doublereal *, doublereal *, integer *);
409 doublereal uhavi, uhbvi, tmpii;
410 integer lwmin;
411 logical wants;
412 doublereal tmpir, tmpri, dummy[1], tmprr;
413 extern doublereal dlapy2_(doublereal *, doublereal *);
414 doublereal dummy1[1];
415 extern doublereal dlamch_(char *);
416 doublereal alphai, alphar;
417 extern /* Subroutine */
418 int dlacpy_(char *, integer *, integer *, doublereal *, integer *, doublereal *, integer *), xerbla_(char *, integer *), dtgexc_(logical *, logical *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, integer *, integer *, doublereal *, integer *, integer *);
419 logical wantbh, wantdf, somcon;
420 doublereal alprqt;
421 extern /* Subroutine */
422 int dtgsyl_(char *, integer *, integer *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, integer *, doublereal *, doublereal *, doublereal *, integer *, integer *, integer *);
423 doublereal smlnum;
424 logical lquery;
425 /* -- LAPACK computational routine (version 3.4.0) -- */
426 /* -- LAPACK is a software package provided by Univ. of Tennessee, -- */
427 /* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- */
428 /* November 2011 */
429 /* .. Scalar Arguments .. */
430 /* .. */
431 /* .. Array Arguments .. */
432 /* .. */
433 /* ===================================================================== */
434 /* .. Parameters .. */
435 /* .. */
436 /* .. Local Scalars .. */
437 /* .. */
438 /* .. Local Arrays .. */
439 /* .. */
440 /* .. External Functions .. */
441 /* .. */
442 /* .. External Subroutines .. */
443 /* .. */
444 /* .. Intrinsic Functions .. */
445 /* .. */
446 /* .. Executable Statements .. */
447 /* Decode and test the input parameters */
448 /* Parameter adjustments */
449 --select;
450 a_dim1 = *lda;
451 a_offset = 1 + a_dim1;
452 a -= a_offset;
453 b_dim1 = *ldb;
454 b_offset = 1 + b_dim1;
455 b -= b_offset;
456 vl_dim1 = *ldvl;
457 vl_offset = 1 + vl_dim1;
458 vl -= vl_offset;
459 vr_dim1 = *ldvr;
460 vr_offset = 1 + vr_dim1;
461 vr -= vr_offset;
462 --s;
463 --dif;
464 --work;
465 --iwork;
466 /* Function Body */
467 wantbh = lsame_(job, "B");
468 wants = lsame_(job, "E") || wantbh;
469 wantdf = lsame_(job, "V") || wantbh;
470 somcon = lsame_(howmny, "S");
471 *info = 0;
472 lquery = *lwork == -1;
473 if (! wants && ! wantdf)
474 {
475 *info = -1;
476 }
477 else if (! lsame_(howmny, "A") && ! somcon)
478 {
479 *info = -2;
480 }
481 else if (*n < 0)
482 {
483 *info = -4;
484 }
485 else if (*lda < max(1,*n))
486 {
487 *info = -6;
488 }
489 else if (*ldb < max(1,*n))
490 {
491 *info = -8;
492 }
493 else if (wants && *ldvl < *n)
494 {
495 *info = -10;
496 }
497 else if (wants && *ldvr < *n)
498 {
499 *info = -12;
500 }
501 else
502 {
503 /* Set M to the number of eigenpairs for which condition numbers */
504 /* are required, and test MM. */
505 if (somcon)
506 {
507 *m = 0;
508 pair = FALSE_;
509 i__1 = *n;
510 for (k = 1;
511 k <= i__1;
512 ++k)
513 {
514 if (pair)
515 {
516 pair = FALSE_;
517 }
518 else
519 {
520 if (k < *n)
521 {
522 if (a[k + 1 + k * a_dim1] == 0.)
523 {
524 if (select[k])
525 {
526 ++(*m);
527 }
528 }
529 else
530 {
531 pair = TRUE_;
532 if (select[k] || select[k + 1])
533 {
534 *m += 2;
535 }
536 }
537 }
538 else
539 {
540 if (select[*n])
541 {
542 ++(*m);
543 }
544 }
545 }
546 /* L10: */
547 }
548 }
549 else
550 {
551 *m = *n;
552 }
553 if (*n == 0)
554 {
555 lwmin = 1;
556 }
557 else if (lsame_(job, "V") || lsame_(job, "B"))
558 {
559 lwmin = (*n << 1) * (*n + 2) + 16;
560 }
561 else
562 {
563 lwmin = *n;
564 }
565 work[1] = (doublereal) lwmin;
566 if (*mm < *m)
567 {
568 *info = -15;
569 }
570 else if (*lwork < lwmin && ! lquery)
571 {
572 *info = -18;
573 }
574 }
575 if (*info != 0)
576 {
577 i__1 = -(*info);
578 xerbla_("DTGSNA", &i__1);
579 return 0;
580 }
581 else if (lquery)
582 {
583 return 0;
584 }
585 /* Quick return if possible */
586 if (*n == 0)
587 {
588 return 0;
589 }
590 /* Get machine constants */
591 eps = dlamch_("P");
592 smlnum = dlamch_("S") / eps;
593 ks = 0;
594 pair = FALSE_;
595 i__1 = *n;
596 for (k = 1;
597 k <= i__1;
598 ++k)
599 {
600 /* Determine whether A(k,k) begins a 1-by-1 or 2-by-2 block. */
601 if (pair)
602 {
603 pair = FALSE_;
604 goto L20;
605 }
606 else
607 {
608 if (k < *n)
609 {
610 pair = a[k + 1 + k * a_dim1] != 0.;
611 }
612 }
613 /* Determine whether condition numbers are required for the k-th */
614 /* eigenpair. */
615 if (somcon)
616 {
617 if (pair)
618 {
619 if (! select[k] && ! select[k + 1])
620 {
621 goto L20;
622 }
623 }
624 else
625 {
626 if (! select[k])
627 {
628 goto L20;
629 }
630 }
631 }
632 ++ks;
633 if (wants)
634 {
635 /* Compute the reciprocal condition number of the k-th */
636 /* eigenvalue. */
637 if (pair)
638 {
639 /* Complex eigenvalue pair. */
640 d__1 = dnrm2_(n, &vr[ks * vr_dim1 + 1], &c__1);
641 d__2 = dnrm2_(n, &vr[(ks + 1) * vr_dim1 + 1], &c__1);
642 rnrm = dlapy2_(&d__1, &d__2);
643 d__1 = dnrm2_(n, &vl[ks * vl_dim1 + 1], &c__1);
644 d__2 = dnrm2_(n, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
645 lnrm = dlapy2_(&d__1, &d__2);
646 dgemv_("N", n, n, &c_b19, &a[a_offset], lda, &vr[ks * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
647 tmprr = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], & c__1);
648 tmpri = ddot_(n, &work[1], &c__1, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
649 dgemv_("N", n, n, &c_b19, &a[a_offset], lda, &vr[(ks + 1) * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
650 tmpii = ddot_(n, &work[1], &c__1, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
651 tmpir = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], & c__1);
652 uhav = tmprr + tmpii;
653 uhavi = tmpir - tmpri;
654 dgemv_("N", n, n, &c_b19, &b[b_offset], ldb, &vr[ks * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
655 tmprr = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], & c__1);
656 tmpri = ddot_(n, &work[1], &c__1, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
657 dgemv_("N", n, n, &c_b19, &b[b_offset], ldb, &vr[(ks + 1) * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
658 tmpii = ddot_(n, &work[1], &c__1, &vl[(ks + 1) * vl_dim1 + 1], &c__1);
659 tmpir = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], & c__1);
660 uhbv = tmprr + tmpii;
661 uhbvi = tmpir - tmpri;
662 uhav = dlapy2_(&uhav, &uhavi);
663 uhbv = dlapy2_(&uhbv, &uhbvi);
664 cond = dlapy2_(&uhav, &uhbv);
665 s[ks] = cond / (rnrm * lnrm);
666 s[ks + 1] = s[ks];
667 }
668 else
669 {
670 /* Real eigenvalue. */
671 rnrm = dnrm2_(n, &vr[ks * vr_dim1 + 1], &c__1);
672 lnrm = dnrm2_(n, &vl[ks * vl_dim1 + 1], &c__1);
673 dgemv_("N", n, n, &c_b19, &a[a_offset], lda, &vr[ks * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
674 uhav = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], &c__1) ;
675 dgemv_("N", n, n, &c_b19, &b[b_offset], ldb, &vr[ks * vr_dim1 + 1], &c__1, &c_b21, &work[1], &c__1);
676 uhbv = ddot_(n, &work[1], &c__1, &vl[ks * vl_dim1 + 1], &c__1) ;
677 cond = dlapy2_(&uhav, &uhbv);
678 if (cond == 0.)
679 {
680 s[ks] = -1.;
681 }
682 else
683 {
684 s[ks] = cond / (rnrm * lnrm);
685 }
686 }
687 }
688 if (wantdf)
689 {
690 if (*n == 1)
691 {
692 dif[ks] = dlapy2_(&a[a_dim1 + 1], &b[b_dim1 + 1]);
693 goto L20;
694 }
695 /* Estimate the reciprocal condition number of the k-th */
696 /* eigenvectors. */
697 if (pair)
698 {
699 /* Copy the 2-by 2 pencil beginning at (A(k,k), B(k, k)). */
700 /* Compute the eigenvalue(s) at position K. */
701 work[1] = a[k + k * a_dim1];
702 work[2] = a[k + 1 + k * a_dim1];
703 work[3] = a[k + (k + 1) * a_dim1];
704 work[4] = a[k + 1 + (k + 1) * a_dim1];
705 work[5] = b[k + k * b_dim1];
706 work[6] = b[k + 1 + k * b_dim1];
707 work[7] = b[k + (k + 1) * b_dim1];
708 work[8] = b[k + 1 + (k + 1) * b_dim1];
709 d__1 = smlnum * eps;
710 dlag2_(&work[1], &c__2, &work[5], &c__2, &d__1, &beta, dummy1, &alphar, dummy, &alphai);
711 alprqt = 1.;
712 c1 = (alphar * alphar + alphai * alphai + beta * beta) * 2.;
713 c2 = beta * 4. * beta * alphai * alphai;
714 root1 = c1 + sqrt(c1 * c1 - c2 * 4.);
715 root2 = c2 / root1;
716 root1 /= 2.;
717 /* Computing MIN */
718 d__1 = sqrt(root1);
719 d__2 = sqrt(root2); // , expr subst
720 cond = min(d__1,d__2);
721 }
722 /* Copy the matrix (A, B) to the array WORK and swap the */
723 /* diagonal block beginning at A(k,k) to the (1,1) position. */
724 dlacpy_("Full", n, n, &a[a_offset], lda, &work[1], n);
725 dlacpy_("Full", n, n, &b[b_offset], ldb, &work[*n * *n + 1], n);
726 ifst = k;
727 ilst = 1;
728 i__2 = *lwork - (*n << 1) * *n;
729 dtgexc_(&c_false, &c_false, n, &work[1], n, &work[*n * *n + 1], n, dummy, &c__1, dummy1, &c__1, &ifst, &ilst, &work[(*n * * n << 1) + 1], &i__2, &ierr);
730 if (ierr > 0)
731 {
732 /* Ill-conditioned problem - swap rejected. */
733 dif[ks] = 0.;
734 }
735 else
736 {
737 /* Reordering successful, solve generalized Sylvester */
738 /* equation for R and L, */
739 /* A22 * R - L * A11 = A12 */
740 /* B22 * R - L * B11 = B12, */
741 /* and compute estimate of Difl((A11,B11), (A22, B22)). */
742 n1 = 1;
743 if (work[2] != 0.)
744 {
745 n1 = 2;
746 }
747 n2 = *n - n1;
748 if (n2 == 0)
749 {
750 dif[ks] = cond;
751 }
752 else
753 {
754 i__ = *n * *n + 1;
755 iz = (*n << 1) * *n + 1;
756 i__2 = *lwork - (*n << 1) * *n;
757 dtgsyl_("N", &c__3, &n2, &n1, &work[*n * n1 + n1 + 1], n, &work[1], n, &work[n1 + 1], n, &work[*n * n1 + n1 + i__], n, &work[i__], n, &work[n1 + i__], n, & scale, &dif[ks], &work[iz + 1], &i__2, &iwork[1], &ierr);
758 if (pair)
759 {
760 /* Computing MIN */
761 d__1 = max(1.,alprqt) * dif[ks];
762 dif[ks] = min(d__1,cond);
763 }
764 }
765 }
766 if (pair)
767 {
768 dif[ks + 1] = dif[ks];
769 }
770 }
771 if (pair)
772 {
773 ++ks;
774 }
775 L20:
776 ;
777 }
778 work[1] = (doublereal) lwmin;
779 return 0;
780 /* End of DTGSNA */
781 }
782 /* dtgsna_ */
783