1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
|
/* strexc.f -- translated by f2c (version 20061008).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
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
*/
#include "f2c.h"
#include "blaswrap.h"
/* Table of constant values */
static integer c__1 = 1;
static integer c__2 = 2;
/* Subroutine */ int strexc_(char *compq, integer *n, real *t, integer *ldt,
real *q, integer *ldq, integer *ifst, integer *ilst, real *work,
integer *info)
{
/* System generated locals */
integer q_dim1, q_offset, t_dim1, t_offset, i__1;
/* Local variables */
integer nbf, nbl, here;
extern logical lsame_(char *, char *);
logical wantq;
extern /* Subroutine */ int xerbla_(char *, integer *), slaexc_(
logical *, integer *, real *, integer *, real *, integer *,
integer *, integer *, integer *, real *, integer *);
integer nbnext;
/* -- LAPACK routine (version 3.2) -- */
/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
/* November 2006 */
/* .. Scalar Arguments .. */
/* .. */
/* .. Array Arguments .. */
/* .. */
/* Purpose */
/* ======= */
/* STREXC reorders the real Schur factorization of a real matrix */
/* A = Q*T*Q**T, so that the diagonal block of T with row index IFST is */
/* moved to row ILST. */
/* The real Schur form T is reordered by an orthogonal similarity */
/* transformation Z**T*T*Z, and optionally the matrix Q of Schur vectors */
/* is updated by postmultiplying it with Z. */
/* T must be in Schur canonical form (as returned by SHSEQR), that is, */
/* block upper triangular with 1-by-1 and 2-by-2 diagonal blocks; each */
/* 2-by-2 diagonal block has its diagonal elements equal and its */
/* off-diagonal elements of opposite sign. */
/* Arguments */
/* ========= */
/* COMPQ (input) CHARACTER*1 */
/* = 'V': update the matrix Q of Schur vectors; */
/* = 'N': do not update Q. */
/* N (input) INTEGER */
/* The order of the matrix T. N >= 0. */
/* T (input/output) REAL array, dimension (LDT,N) */
/* On entry, the upper quasi-triangular matrix T, in Schur */
/* Schur canonical form. */
/* On exit, the reordered upper quasi-triangular matrix, again */
/* in Schur canonical form. */
/* LDT (input) INTEGER */
/* The leading dimension of the array T. LDT >= max(1,N). */
/* Q (input/output) REAL array, dimension (LDQ,N) */
/* On entry, if COMPQ = 'V', the matrix Q of Schur vectors. */
/* On exit, if COMPQ = 'V', Q has been postmultiplied by the */
/* orthogonal transformation matrix Z which reorders T. */
/* If COMPQ = 'N', Q is not referenced. */
/* LDQ (input) INTEGER */
/* The leading dimension of the array Q. LDQ >= max(1,N). */
/* IFST (input/output) INTEGER */
/* ILST (input/output) INTEGER */
/* Specify the reordering of the diagonal blocks of T. */
/* The block with row index IFST is moved to row ILST, by a */
/* sequence of transpositions between adjacent blocks. */
/* On exit, if IFST pointed on entry to the second row of a */
/* 2-by-2 block, it is changed to point to the first row; ILST */
/* always points to the first row of the block in its final */
/* position (which may differ from its input value by +1 or -1). */
/* 1 <= IFST <= N; 1 <= ILST <= N. */
/* WORK (workspace) REAL array, dimension (N) */
/* INFO (output) INTEGER */
/* = 0: successful exit */
/* < 0: if INFO = -i, the i-th argument had an illegal value */
/* = 1: two adjacent blocks were too close to swap (the problem */
/* is very ill-conditioned); T may have been partially */
/* reordered, and ILST points to the first row of the */
/* current position of the block being moved. */
/* ===================================================================== */
/* .. Parameters .. */
/* .. */
/* .. Local Scalars .. */
/* .. */
/* .. External Functions .. */
/* .. */
/* .. External Subroutines .. */
/* .. */
/* .. Intrinsic Functions .. */
/* .. */
/* .. Executable Statements .. */
/* Decode and test the input arguments. */
/* Parameter adjustments */
t_dim1 = *ldt;
t_offset = 1 + t_dim1;
t -= t_offset;
q_dim1 = *ldq;
q_offset = 1 + q_dim1;
q -= q_offset;
--work;
/* Function Body */
*info = 0;
wantq = lsame_(compq, "V");
if (! wantq && ! lsame_(compq, "N")) {
*info = -1;
} else if (*n < 0) {
*info = -2;
} else if (*ldt < max(1,*n)) {
*info = -4;
} else if (*ldq < 1 || wantq && *ldq < max(1,*n)) {
*info = -6;
} else if (*ifst < 1 || *ifst > *n) {
*info = -7;
} else if (*ilst < 1 || *ilst > *n) {
*info = -8;
}
if (*info != 0) {
i__1 = -(*info);
xerbla_("STREXC", &i__1);
return 0;
}
/* Quick return if possible */
if (*n <= 1) {
return 0;
}
/* Determine the first row of specified block */
/* and find out it is 1 by 1 or 2 by 2. */
if (*ifst > 1) {
if (t[*ifst + (*ifst - 1) * t_dim1] != 0.f) {
--(*ifst);
}
}
nbf = 1;
if (*ifst < *n) {
if (t[*ifst + 1 + *ifst * t_dim1] != 0.f) {
nbf = 2;
}
}
/* Determine the first row of the final block */
/* and find out it is 1 by 1 or 2 by 2. */
if (*ilst > 1) {
if (t[*ilst + (*ilst - 1) * t_dim1] != 0.f) {
--(*ilst);
}
}
nbl = 1;
if (*ilst < *n) {
if (t[*ilst + 1 + *ilst * t_dim1] != 0.f) {
nbl = 2;
}
}
if (*ifst == *ilst) {
return 0;
}
if (*ifst < *ilst) {
/* Update ILST */
if (nbf == 2 && nbl == 1) {
--(*ilst);
}
if (nbf == 1 && nbl == 2) {
++(*ilst);
}
here = *ifst;
L10:
/* Swap block with next one below */
if (nbf == 1 || nbf == 2) {
/* Current block either 1 by 1 or 2 by 2 */
nbnext = 1;
if (here + nbf + 1 <= *n) {
if (t[here + nbf + 1 + (here + nbf) * t_dim1] != 0.f) {
nbnext = 2;
}
}
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &here, &
nbf, &nbnext, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
here += nbnext;
/* Test if 2 by 2 block breaks into two 1 by 1 blocks */
if (nbf == 2) {
if (t[here + 1 + here * t_dim1] == 0.f) {
nbf = 3;
}
}
} else {
/* Current block consists of two 1 by 1 blocks each of which */
/* must be swapped individually */
nbnext = 1;
if (here + 3 <= *n) {
if (t[here + 3 + (here + 2) * t_dim1] != 0.f) {
nbnext = 2;
}
}
i__1 = here + 1;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &i__1, &
c__1, &nbnext, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
if (nbnext == 1) {
/* Swap two 1 by 1 blocks, no problems possible */
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
here, &c__1, &nbnext, &work[1], info);
++here;
} else {
/* Recompute NBNEXT in case 2 by 2 split */
if (t[here + 2 + (here + 1) * t_dim1] == 0.f) {
nbnext = 1;
}
if (nbnext == 2) {
/* 2 by 2 Block did not split */
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
here, &c__1, &nbnext, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
here += 2;
} else {
/* 2 by 2 Block did split */
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
here, &c__1, &c__1, &work[1], info);
i__1 = here + 1;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
i__1, &c__1, &c__1, &work[1], info);
here += 2;
}
}
}
if (here < *ilst) {
goto L10;
}
} else {
here = *ifst;
L20:
/* Swap block with next one above */
if (nbf == 1 || nbf == 2) {
/* Current block either 1 by 1 or 2 by 2 */
nbnext = 1;
if (here >= 3) {
if (t[here - 1 + (here - 2) * t_dim1] != 0.f) {
nbnext = 2;
}
}
i__1 = here - nbnext;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &i__1, &
nbnext, &nbf, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
here -= nbnext;
/* Test if 2 by 2 block breaks into two 1 by 1 blocks */
if (nbf == 2) {
if (t[here + 1 + here * t_dim1] == 0.f) {
nbf = 3;
}
}
} else {
/* Current block consists of two 1 by 1 blocks each of which */
/* must be swapped individually */
nbnext = 1;
if (here >= 3) {
if (t[here - 1 + (here - 2) * t_dim1] != 0.f) {
nbnext = 2;
}
}
i__1 = here - nbnext;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &i__1, &
nbnext, &c__1, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
if (nbnext == 1) {
/* Swap two 1 by 1 blocks, no problems possible */
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
here, &nbnext, &c__1, &work[1], info);
--here;
} else {
/* Recompute NBNEXT in case 2 by 2 split */
if (t[here + (here - 1) * t_dim1] == 0.f) {
nbnext = 1;
}
if (nbnext == 2) {
/* 2 by 2 Block did not split */
i__1 = here - 1;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
i__1, &c__2, &c__1, &work[1], info);
if (*info != 0) {
*ilst = here;
return 0;
}
here += -2;
} else {
/* 2 by 2 Block did split */
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
here, &c__1, &c__1, &work[1], info);
i__1 = here - 1;
slaexc_(&wantq, n, &t[t_offset], ldt, &q[q_offset], ldq, &
i__1, &c__1, &c__1, &work[1], info);
here += -2;
}
}
}
if (here > *ilst) {
goto L20;
}
}
*ilst = here;
return 0;
/* End of STREXC */
} /* strexc_ */
|
