1: *> \brief \b ZUNBDB
2: *
3: * =========== DOCUMENTATION ===========
4: *
5: * Online html documentation available at
6: * http://www.netlib.org/lapack/explore-html/
7: *
8: *> \htmlonly
9: *> Download ZUNBDB + dependencies
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11: *> [TGZ]</a>
12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/zunbdb.f">
13: *> [ZIP]</a>
14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/zunbdb.f">
15: *> [TXT]</a>
16: *> \endhtmlonly
17: *
18: * Definition:
19: * ===========
20: *
21: * SUBROUTINE ZUNBDB( TRANS, SIGNS, M, P, Q, X11, LDX11, X12, LDX12,
22: * X21, LDX21, X22, LDX22, THETA, PHI, TAUP1,
23: * TAUP2, TAUQ1, TAUQ2, WORK, LWORK, INFO )
24: *
25: * .. Scalar Arguments ..
26: * CHARACTER SIGNS, TRANS
27: * INTEGER INFO, LDX11, LDX12, LDX21, LDX22, LWORK, M, P,
28: * $ Q
29: * ..
30: * .. Array Arguments ..
31: * DOUBLE PRECISION PHI( * ), THETA( * )
32: * COMPLEX*16 TAUP1( * ), TAUP2( * ), TAUQ1( * ), TAUQ2( * ),
33: * $ WORK( * ), X11( LDX11, * ), X12( LDX12, * ),
34: * $ X21( LDX21, * ), X22( LDX22, * )
35: * ..
36: *
37: *
38: *> \par Purpose:
39: * =============
40: *>
41: *> \verbatim
42: *>
43: *> ZUNBDB simultaneously bidiagonalizes the blocks of an M-by-M
44: *> partitioned unitary matrix X:
45: *>
46: *> [ B11 | B12 0 0 ]
47: *> [ X11 | X12 ] [ P1 | ] [ 0 | 0 -I 0 ] [ Q1 | ]**H
48: *> X = [-----------] = [---------] [----------------] [---------] .
49: *> [ X21 | X22 ] [ | P2 ] [ B21 | B22 0 0 ] [ | Q2 ]
50: *> [ 0 | 0 0 I ]
51: *>
52: *> X11 is P-by-Q. Q must be no larger than P, M-P, or M-Q. (If this is
53: *> not the case, then X must be transposed and/or permuted. This can be
54: *> done in constant time using the TRANS and SIGNS options. See ZUNCSD
55: *> for details.)
56: *>
57: *> The unitary matrices P1, P2, Q1, and Q2 are P-by-P, (M-P)-by-
58: *> (M-P), Q-by-Q, and (M-Q)-by-(M-Q), respectively. They are
59: *> represented implicitly by Householder vectors.
60: *>
61: *> B11, B12, B21, and B22 are Q-by-Q bidiagonal matrices represented
62: *> implicitly by angles THETA, PHI.
63: *> \endverbatim
64: *
65: * Arguments:
66: * ==========
67: *
68: *> \param[in] TRANS
69: *> \verbatim
70: *> TRANS is CHARACTER
71: *> = 'T': X, U1, U2, V1T, and V2T are stored in row-major
72: *> order;
73: *> otherwise: X, U1, U2, V1T, and V2T are stored in column-
74: *> major order.
75: *> \endverbatim
76: *>
77: *> \param[in] SIGNS
78: *> \verbatim
79: *> SIGNS is CHARACTER
80: *> = 'O': The lower-left block is made nonpositive (the
81: *> "other" convention);
82: *> otherwise: The upper-right block is made nonpositive (the
83: *> "default" convention).
84: *> \endverbatim
85: *>
86: *> \param[in] M
87: *> \verbatim
88: *> M is INTEGER
89: *> The number of rows and columns in X.
90: *> \endverbatim
91: *>
92: *> \param[in] P
93: *> \verbatim
94: *> P is INTEGER
95: *> The number of rows in X11 and X12. 0 <= P <= M.
96: *> \endverbatim
97: *>
98: *> \param[in] Q
99: *> \verbatim
100: *> Q is INTEGER
101: *> The number of columns in X11 and X21. 0 <= Q <=
102: *> MIN(P,M-P,M-Q).
103: *> \endverbatim
104: *>
105: *> \param[in,out] X11
106: *> \verbatim
107: *> X11 is COMPLEX*16 array, dimension (LDX11,Q)
108: *> On entry, the top-left block of the unitary matrix to be
109: *> reduced. On exit, the form depends on TRANS:
110: *> If TRANS = 'N', then
111: *> the columns of tril(X11) specify reflectors for P1,
112: *> the rows of triu(X11,1) specify reflectors for Q1;
113: *> else TRANS = 'T', and
114: *> the rows of triu(X11) specify reflectors for P1,
115: *> the columns of tril(X11,-1) specify reflectors for Q1.
116: *> \endverbatim
117: *>
118: *> \param[in] LDX11
119: *> \verbatim
120: *> LDX11 is INTEGER
121: *> The leading dimension of X11. If TRANS = 'N', then LDX11 >=
122: *> P; else LDX11 >= Q.
123: *> \endverbatim
124: *>
125: *> \param[in,out] X12
126: *> \verbatim
127: *> X12 is COMPLEX*16 array, dimension (LDX12,M-Q)
128: *> On entry, the top-right block of the unitary matrix to
129: *> be reduced. On exit, the form depends on TRANS:
130: *> If TRANS = 'N', then
131: *> the rows of triu(X12) specify the first P reflectors for
132: *> Q2;
133: *> else TRANS = 'T', and
134: *> the columns of tril(X12) specify the first P reflectors
135: *> for Q2.
136: *> \endverbatim
137: *>
138: *> \param[in] LDX12
139: *> \verbatim
140: *> LDX12 is INTEGER
141: *> The leading dimension of X12. If TRANS = 'N', then LDX12 >=
142: *> P; else LDX11 >= M-Q.
143: *> \endverbatim
144: *>
145: *> \param[in,out] X21
146: *> \verbatim
147: *> X21 is COMPLEX*16 array, dimension (LDX21,Q)
148: *> On entry, the bottom-left block of the unitary matrix to
149: *> be reduced. On exit, the form depends on TRANS:
150: *> If TRANS = 'N', then
151: *> the columns of tril(X21) specify reflectors for P2;
152: *> else TRANS = 'T', and
153: *> the rows of triu(X21) specify reflectors for P2.
154: *> \endverbatim
155: *>
156: *> \param[in] LDX21
157: *> \verbatim
158: *> LDX21 is INTEGER
159: *> The leading dimension of X21. If TRANS = 'N', then LDX21 >=
160: *> M-P; else LDX21 >= Q.
161: *> \endverbatim
162: *>
163: *> \param[in,out] X22
164: *> \verbatim
165: *> X22 is COMPLEX*16 array, dimension (LDX22,M-Q)
166: *> On entry, the bottom-right block of the unitary matrix to
167: *> be reduced. On exit, the form depends on TRANS:
168: *> If TRANS = 'N', then
169: *> the rows of triu(X22(Q+1:M-P,P+1:M-Q)) specify the last
170: *> M-P-Q reflectors for Q2,
171: *> else TRANS = 'T', and
172: *> the columns of tril(X22(P+1:M-Q,Q+1:M-P)) specify the last
173: *> M-P-Q reflectors for P2.
174: *> \endverbatim
175: *>
176: *> \param[in] LDX22
177: *> \verbatim
178: *> LDX22 is INTEGER
179: *> The leading dimension of X22. If TRANS = 'N', then LDX22 >=
180: *> M-P; else LDX22 >= M-Q.
181: *> \endverbatim
182: *>
183: *> \param[out] THETA
184: *> \verbatim
185: *> THETA is DOUBLE PRECISION array, dimension (Q)
186: *> The entries of the bidiagonal blocks B11, B12, B21, B22 can
187: *> be computed from the angles THETA and PHI. See Further
188: *> Details.
189: *> \endverbatim
190: *>
191: *> \param[out] PHI
192: *> \verbatim
193: *> PHI is DOUBLE PRECISION array, dimension (Q-1)
194: *> The entries of the bidiagonal blocks B11, B12, B21, B22 can
195: *> be computed from the angles THETA and PHI. See Further
196: *> Details.
197: *> \endverbatim
198: *>
199: *> \param[out] TAUP1
200: *> \verbatim
201: *> TAUP1 is COMPLEX*16 array, dimension (P)
202: *> The scalar factors of the elementary reflectors that define
203: *> P1.
204: *> \endverbatim
205: *>
206: *> \param[out] TAUP2
207: *> \verbatim
208: *> TAUP2 is COMPLEX*16 array, dimension (M-P)
209: *> The scalar factors of the elementary reflectors that define
210: *> P2.
211: *> \endverbatim
212: *>
213: *> \param[out] TAUQ1
214: *> \verbatim
215: *> TAUQ1 is COMPLEX*16 array, dimension (Q)
216: *> The scalar factors of the elementary reflectors that define
217: *> Q1.
218: *> \endverbatim
219: *>
220: *> \param[out] TAUQ2
221: *> \verbatim
222: *> TAUQ2 is COMPLEX*16 array, dimension (M-Q)
223: *> The scalar factors of the elementary reflectors that define
224: *> Q2.
225: *> \endverbatim
226: *>
227: *> \param[out] WORK
228: *> \verbatim
229: *> WORK is COMPLEX*16 array, dimension (LWORK)
230: *> \endverbatim
231: *>
232: *> \param[in] LWORK
233: *> \verbatim
234: *> LWORK is INTEGER
235: *> The dimension of the array WORK. LWORK >= M-Q.
236: *>
237: *> If LWORK = -1, then a workspace query is assumed; the routine
238: *> only calculates the optimal size of the WORK array, returns
239: *> this value as the first entry of the WORK array, and no error
240: *> message related to LWORK is issued by XERBLA.
241: *> \endverbatim
242: *>
243: *> \param[out] INFO
244: *> \verbatim
245: *> INFO is INTEGER
246: *> = 0: successful exit.
247: *> < 0: if INFO = -i, the i-th argument had an illegal value.
248: *> \endverbatim
249: *
250: * Authors:
251: * ========
252: *
253: *> \author Univ. of Tennessee
254: *> \author Univ. of California Berkeley
255: *> \author Univ. of Colorado Denver
256: *> \author NAG Ltd.
257: *
258: *> \date November 2011
259: *
260: *> \ingroup complex16OTHERcomputational
261: *
262: *> \par Further Details:
263: * =====================
264: *>
265: *> \verbatim
266: *>
267: *> The bidiagonal blocks B11, B12, B21, and B22 are represented
268: *> implicitly by angles THETA(1), ..., THETA(Q) and PHI(1), ...,
269: *> PHI(Q-1). B11 and B21 are upper bidiagonal, while B21 and B22 are
270: *> lower bidiagonal. Every entry in each bidiagonal band is a product
271: *> of a sine or cosine of a THETA with a sine or cosine of a PHI. See
272: *> [1] or ZUNCSD for details.
273: *>
274: *> P1, P2, Q1, and Q2 are represented as products of elementary
275: *> reflectors. See ZUNCSD for details on generating P1, P2, Q1, and Q2
276: *> using ZUNGQR and ZUNGLQ.
277: *> \endverbatim
278: *
279: *> \par References:
280: * ================
281: *>
282: *> [1] Brian D. Sutton. Computing the complete CS decomposition. Numer.
283: *> Algorithms, 50(1):33-65, 2009.
284: *>
285: * =====================================================================
286: SUBROUTINE ZUNBDB( TRANS, SIGNS, M, P, Q, X11, LDX11, X12, LDX12,
287: $ X21, LDX21, X22, LDX22, THETA, PHI, TAUP1,
288: $ TAUP2, TAUQ1, TAUQ2, WORK, LWORK, INFO )
289: *
290: * -- LAPACK computational routine (version 3.4.0) --
291: * -- LAPACK is a software package provided by Univ. of Tennessee, --
292: * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
293: * November 2011
294: *
295: * .. Scalar Arguments ..
296: CHARACTER SIGNS, TRANS
297: INTEGER INFO, LDX11, LDX12, LDX21, LDX22, LWORK, M, P,
298: $ Q
299: * ..
300: * .. Array Arguments ..
301: DOUBLE PRECISION PHI( * ), THETA( * )
302: COMPLEX*16 TAUP1( * ), TAUP2( * ), TAUQ1( * ), TAUQ2( * ),
303: $ WORK( * ), X11( LDX11, * ), X12( LDX12, * ),
304: $ X21( LDX21, * ), X22( LDX22, * )
305: * ..
306: *
307: * ====================================================================
308: *
309: * .. Parameters ..
310: DOUBLE PRECISION REALONE
311: PARAMETER ( REALONE = 1.0D0 )
312: COMPLEX*16 ONE
313: PARAMETER ( ONE = (1.0D0,0.0D0) )
314: * ..
315: * .. Local Scalars ..
316: LOGICAL COLMAJOR, LQUERY
317: INTEGER I, LWORKMIN, LWORKOPT
318: DOUBLE PRECISION Z1, Z2, Z3, Z4
319: * ..
320: * .. External Subroutines ..
321: EXTERNAL ZAXPY, ZLARF, ZLARFGP, ZSCAL, XERBLA
322: EXTERNAL ZLACGV
323: *
324: * ..
325: * .. External Functions ..
326: DOUBLE PRECISION DZNRM2
327: LOGICAL LSAME
328: EXTERNAL DZNRM2, LSAME
329: * ..
330: * .. Intrinsic Functions
331: INTRINSIC ATAN2, COS, MAX, MIN, SIN
332: INTRINSIC DCMPLX, DCONJG
333: * ..
334: * .. Executable Statements ..
335: *
336: * Test input arguments
337: *
338: INFO = 0
339: COLMAJOR = .NOT. LSAME( TRANS, 'T' )
340: IF( .NOT. LSAME( SIGNS, 'O' ) ) THEN
341: Z1 = REALONE
342: Z2 = REALONE
343: Z3 = REALONE
344: Z4 = REALONE
345: ELSE
346: Z1 = REALONE
347: Z2 = -REALONE
348: Z3 = REALONE
349: Z4 = -REALONE
350: END IF
351: LQUERY = LWORK .EQ. -1
352: *
353: IF( M .LT. 0 ) THEN
354: INFO = -3
355: ELSE IF( P .LT. 0 .OR. P .GT. M ) THEN
356: INFO = -4
357: ELSE IF( Q .LT. 0 .OR. Q .GT. P .OR. Q .GT. M-P .OR.
358: $ Q .GT. M-Q ) THEN
359: INFO = -5
360: ELSE IF( COLMAJOR .AND. LDX11 .LT. MAX( 1, P ) ) THEN
361: INFO = -7
362: ELSE IF( .NOT.COLMAJOR .AND. LDX11 .LT. MAX( 1, Q ) ) THEN
363: INFO = -7
364: ELSE IF( COLMAJOR .AND. LDX12 .LT. MAX( 1, P ) ) THEN
365: INFO = -9
366: ELSE IF( .NOT.COLMAJOR .AND. LDX12 .LT. MAX( 1, M-Q ) ) THEN
367: INFO = -9
368: ELSE IF( COLMAJOR .AND. LDX21 .LT. MAX( 1, M-P ) ) THEN
369: INFO = -11
370: ELSE IF( .NOT.COLMAJOR .AND. LDX21 .LT. MAX( 1, Q ) ) THEN
371: INFO = -11
372: ELSE IF( COLMAJOR .AND. LDX22 .LT. MAX( 1, M-P ) ) THEN
373: INFO = -13
374: ELSE IF( .NOT.COLMAJOR .AND. LDX22 .LT. MAX( 1, M-Q ) ) THEN
375: INFO = -13
376: END IF
377: *
378: * Compute workspace
379: *
380: IF( INFO .EQ. 0 ) THEN
381: LWORKOPT = M - Q
382: LWORKMIN = M - Q
383: WORK(1) = LWORKOPT
384: IF( LWORK .LT. LWORKMIN .AND. .NOT. LQUERY ) THEN
385: INFO = -21
386: END IF
387: END IF
388: IF( INFO .NE. 0 ) THEN
389: CALL XERBLA( 'xORBDB', -INFO )
390: RETURN
391: ELSE IF( LQUERY ) THEN
392: RETURN
393: END IF
394: *
395: * Handle column-major and row-major separately
396: *
397: IF( COLMAJOR ) THEN
398: *
399: * Reduce columns 1, ..., Q of X11, X12, X21, and X22
400: *
401: DO I = 1, Q
402: *
403: IF( I .EQ. 1 ) THEN
404: CALL ZSCAL( P-I+1, DCMPLX( Z1, 0.0D0 ), X11(I,I), 1 )
405: ELSE
406: CALL ZSCAL( P-I+1, DCMPLX( Z1*COS(PHI(I-1)), 0.0D0 ),
407: $ X11(I,I), 1 )
408: CALL ZAXPY( P-I+1, DCMPLX( -Z1*Z3*Z4*SIN(PHI(I-1)),
409: $ 0.0D0 ), X12(I,I-1), 1, X11(I,I), 1 )
410: END IF
411: IF( I .EQ. 1 ) THEN
412: CALL ZSCAL( M-P-I+1, DCMPLX( Z2, 0.0D0 ), X21(I,I), 1 )
413: ELSE
414: CALL ZSCAL( M-P-I+1, DCMPLX( Z2*COS(PHI(I-1)), 0.0D0 ),
415: $ X21(I,I), 1 )
416: CALL ZAXPY( M-P-I+1, DCMPLX( -Z2*Z3*Z4*SIN(PHI(I-1)),
417: $ 0.0D0 ), X22(I,I-1), 1, X21(I,I), 1 )
418: END IF
419: *
420: THETA(I) = ATAN2( DZNRM2( M-P-I+1, X21(I,I), 1 ),
421: $ DZNRM2( P-I+1, X11(I,I), 1 ) )
422: *
423: CALL ZLARFGP( P-I+1, X11(I,I), X11(I+1,I), 1, TAUP1(I) )
424: X11(I,I) = ONE
425: CALL ZLARFGP( M-P-I+1, X21(I,I), X21(I+1,I), 1, TAUP2(I) )
426: X21(I,I) = ONE
427: *
428: CALL ZLARF( 'L', P-I+1, Q-I, X11(I,I), 1, DCONJG(TAUP1(I)),
429: $ X11(I,I+1), LDX11, WORK )
430: CALL ZLARF( 'L', P-I+1, M-Q-I+1, X11(I,I), 1,
431: $ DCONJG(TAUP1(I)), X12(I,I), LDX12, WORK )
432: CALL ZLARF( 'L', M-P-I+1, Q-I, X21(I,I), 1,
433: $ DCONJG(TAUP2(I)), X21(I,I+1), LDX21, WORK )
434: CALL ZLARF( 'L', M-P-I+1, M-Q-I+1, X21(I,I), 1,
435: $ DCONJG(TAUP2(I)), X22(I,I), LDX22, WORK )
436: *
437: IF( I .LT. Q ) THEN
438: CALL ZSCAL( Q-I, DCMPLX( -Z1*Z3*SIN(THETA(I)), 0.0D0 ),
439: $ X11(I,I+1), LDX11 )
440: CALL ZAXPY( Q-I, DCMPLX( Z2*Z3*COS(THETA(I)), 0.0D0 ),
441: $ X21(I,I+1), LDX21, X11(I,I+1), LDX11 )
442: END IF
443: CALL ZSCAL( M-Q-I+1, DCMPLX( -Z1*Z4*SIN(THETA(I)), 0.0D0 ),
444: $ X12(I,I), LDX12 )
445: CALL ZAXPY( M-Q-I+1, DCMPLX( Z2*Z4*COS(THETA(I)), 0.0D0 ),
446: $ X22(I,I), LDX22, X12(I,I), LDX12 )
447: *
448: IF( I .LT. Q )
449: $ PHI(I) = ATAN2( DZNRM2( Q-I, X11(I,I+1), LDX11 ),
450: $ DZNRM2( M-Q-I+1, X12(I,I), LDX12 ) )
451: *
452: IF( I .LT. Q ) THEN
453: CALL ZLACGV( Q-I, X11(I,I+1), LDX11 )
454: CALL ZLARFGP( Q-I, X11(I,I+1), X11(I,I+2), LDX11,
455: $ TAUQ1(I) )
456: X11(I,I+1) = ONE
457: END IF
458: CALL ZLACGV( M-Q-I+1, X12(I,I), LDX12 )
459: CALL ZLARFGP( M-Q-I+1, X12(I,I), X12(I,I+1), LDX12,
460: $ TAUQ2(I) )
461: X12(I,I) = ONE
462: *
463: IF( I .LT. Q ) THEN
464: CALL ZLARF( 'R', P-I, Q-I, X11(I,I+1), LDX11, TAUQ1(I),
465: $ X11(I+1,I+1), LDX11, WORK )
466: CALL ZLARF( 'R', M-P-I, Q-I, X11(I,I+1), LDX11, TAUQ1(I),
467: $ X21(I+1,I+1), LDX21, WORK )
468: END IF
469: CALL ZLARF( 'R', P-I, M-Q-I+1, X12(I,I), LDX12, TAUQ2(I),
470: $ X12(I+1,I), LDX12, WORK )
471: CALL ZLARF( 'R', M-P-I, M-Q-I+1, X12(I,I), LDX12, TAUQ2(I),
472: $ X22(I+1,I), LDX22, WORK )
473: *
474: IF( I .LT. Q )
475: $ CALL ZLACGV( Q-I, X11(I,I+1), LDX11 )
476: CALL ZLACGV( M-Q-I+1, X12(I,I), LDX12 )
477: *
478: END DO
479: *
480: * Reduce columns Q + 1, ..., P of X12, X22
481: *
482: DO I = Q + 1, P
483: *
484: CALL ZSCAL( M-Q-I+1, DCMPLX( -Z1*Z4, 0.0D0 ), X12(I,I),
485: $ LDX12 )
486: CALL ZLACGV( M-Q-I+1, X12(I,I), LDX12 )
487: CALL ZLARFGP( M-Q-I+1, X12(I,I), X12(I,I+1), LDX12,
488: $ TAUQ2(I) )
489: X12(I,I) = ONE
490: *
491: CALL ZLARF( 'R', P-I, M-Q-I+1, X12(I,I), LDX12, TAUQ2(I),
492: $ X12(I+1,I), LDX12, WORK )
493: IF( M-P-Q .GE. 1 )
494: $ CALL ZLARF( 'R', M-P-Q, M-Q-I+1, X12(I,I), LDX12,
495: $ TAUQ2(I), X22(Q+1,I), LDX22, WORK )
496: *
497: CALL ZLACGV( M-Q-I+1, X12(I,I), LDX12 )
498: *
499: END DO
500: *
501: * Reduce columns P + 1, ..., M - Q of X12, X22
502: *
503: DO I = 1, M - P - Q
504: *
505: CALL ZSCAL( M-P-Q-I+1, DCMPLX( Z2*Z4, 0.0D0 ),
506: $ X22(Q+I,P+I), LDX22 )
507: CALL ZLACGV( M-P-Q-I+1, X22(Q+I,P+I), LDX22 )
508: CALL ZLARFGP( M-P-Q-I+1, X22(Q+I,P+I), X22(Q+I,P+I+1),
509: $ LDX22, TAUQ2(P+I) )
510: X22(Q+I,P+I) = ONE
511: CALL ZLARF( 'R', M-P-Q-I, M-P-Q-I+1, X22(Q+I,P+I), LDX22,
512: $ TAUQ2(P+I), X22(Q+I+1,P+I), LDX22, WORK )
513: *
514: CALL ZLACGV( M-P-Q-I+1, X22(Q+I,P+I), LDX22 )
515: *
516: END DO
517: *
518: ELSE
519: *
520: * Reduce columns 1, ..., Q of X11, X12, X21, X22
521: *
522: DO I = 1, Q
523: *
524: IF( I .EQ. 1 ) THEN
525: CALL ZSCAL( P-I+1, DCMPLX( Z1, 0.0D0 ), X11(I,I),
526: $ LDX11 )
527: ELSE
528: CALL ZSCAL( P-I+1, DCMPLX( Z1*COS(PHI(I-1)), 0.0D0 ),
529: $ X11(I,I), LDX11 )
530: CALL ZAXPY( P-I+1, DCMPLX( -Z1*Z3*Z4*SIN(PHI(I-1)),
531: $ 0.0D0 ), X12(I-1,I), LDX12, X11(I,I), LDX11 )
532: END IF
533: IF( I .EQ. 1 ) THEN
534: CALL ZSCAL( M-P-I+1, DCMPLX( Z2, 0.0D0 ), X21(I,I),
535: $ LDX21 )
536: ELSE
537: CALL ZSCAL( M-P-I+1, DCMPLX( Z2*COS(PHI(I-1)), 0.0D0 ),
538: $ X21(I,I), LDX21 )
539: CALL ZAXPY( M-P-I+1, DCMPLX( -Z2*Z3*Z4*SIN(PHI(I-1)),
540: $ 0.0D0 ), X22(I-1,I), LDX22, X21(I,I), LDX21 )
541: END IF
542: *
543: THETA(I) = ATAN2( DZNRM2( M-P-I+1, X21(I,I), LDX21 ),
544: $ DZNRM2( P-I+1, X11(I,I), LDX11 ) )
545: *
546: CALL ZLACGV( P-I+1, X11(I,I), LDX11 )
547: CALL ZLACGV( M-P-I+1, X21(I,I), LDX21 )
548: *
549: CALL ZLARFGP( P-I+1, X11(I,I), X11(I,I+1), LDX11, TAUP1(I) )
550: X11(I,I) = ONE
551: CALL ZLARFGP( M-P-I+1, X21(I,I), X21(I,I+1), LDX21,
552: $ TAUP2(I) )
553: X21(I,I) = ONE
554: *
555: CALL ZLARF( 'R', Q-I, P-I+1, X11(I,I), LDX11, TAUP1(I),
556: $ X11(I+1,I), LDX11, WORK )
557: CALL ZLARF( 'R', M-Q-I+1, P-I+1, X11(I,I), LDX11, TAUP1(I),
558: $ X12(I,I), LDX12, WORK )
559: CALL ZLARF( 'R', Q-I, M-P-I+1, X21(I,I), LDX21, TAUP2(I),
560: $ X21(I+1,I), LDX21, WORK )
561: CALL ZLARF( 'R', M-Q-I+1, M-P-I+1, X21(I,I), LDX21,
562: $ TAUP2(I), X22(I,I), LDX22, WORK )
563: *
564: CALL ZLACGV( P-I+1, X11(I,I), LDX11 )
565: CALL ZLACGV( M-P-I+1, X21(I,I), LDX21 )
566: *
567: IF( I .LT. Q ) THEN
568: CALL ZSCAL( Q-I, DCMPLX( -Z1*Z3*SIN(THETA(I)), 0.0D0 ),
569: $ X11(I+1,I), 1 )
570: CALL ZAXPY( Q-I, DCMPLX( Z2*Z3*COS(THETA(I)), 0.0D0 ),
571: $ X21(I+1,I), 1, X11(I+1,I), 1 )
572: END IF
573: CALL ZSCAL( M-Q-I+1, DCMPLX( -Z1*Z4*SIN(THETA(I)), 0.0D0 ),
574: $ X12(I,I), 1 )
575: CALL ZAXPY( M-Q-I+1, DCMPLX( Z2*Z4*COS(THETA(I)), 0.0D0 ),
576: $ X22(I,I), 1, X12(I,I), 1 )
577: *
578: IF( I .LT. Q )
579: $ PHI(I) = ATAN2( DZNRM2( Q-I, X11(I+1,I), 1 ),
580: $ DZNRM2( M-Q-I+1, X12(I,I), 1 ) )
581: *
582: IF( I .LT. Q ) THEN
583: CALL ZLARFGP( Q-I, X11(I+1,I), X11(I+2,I), 1, TAUQ1(I) )
584: X11(I+1,I) = ONE
585: END IF
586: CALL ZLARFGP( M-Q-I+1, X12(I,I), X12(I+1,I), 1, TAUQ2(I) )
587: X12(I,I) = ONE
588: *
589: IF( I .LT. Q ) THEN
590: CALL ZLARF( 'L', Q-I, P-I, X11(I+1,I), 1,
591: $ DCONJG(TAUQ1(I)), X11(I+1,I+1), LDX11, WORK )
592: CALL ZLARF( 'L', Q-I, M-P-I, X11(I+1,I), 1,
593: $ DCONJG(TAUQ1(I)), X21(I+1,I+1), LDX21, WORK )
594: END IF
595: CALL ZLARF( 'L', M-Q-I+1, P-I, X12(I,I), 1,
596: $ DCONJG(TAUQ2(I)), X12(I,I+1), LDX12, WORK )
597: CALL ZLARF( 'L', M-Q-I+1, M-P-I, X12(I,I), 1,
598: $ DCONJG(TAUQ2(I)), X22(I,I+1), LDX22, WORK )
599: *
600: END DO
601: *
602: * Reduce columns Q + 1, ..., P of X12, X22
603: *
604: DO I = Q + 1, P
605: *
606: CALL ZSCAL( M-Q-I+1, DCMPLX( -Z1*Z4, 0.0D0 ), X12(I,I), 1 )
607: CALL ZLARFGP( M-Q-I+1, X12(I,I), X12(I+1,I), 1, TAUQ2(I) )
608: X12(I,I) = ONE
609: *
610: CALL ZLARF( 'L', M-Q-I+1, P-I, X12(I,I), 1,
611: $ DCONJG(TAUQ2(I)), X12(I,I+1), LDX12, WORK )
612: IF( M-P-Q .GE. 1 )
613: $ CALL ZLARF( 'L', M-Q-I+1, M-P-Q, X12(I,I), 1,
614: $ DCONJG(TAUQ2(I)), X22(I,Q+1), LDX22, WORK )
615: *
616: END DO
617: *
618: * Reduce columns P + 1, ..., M - Q of X12, X22
619: *
620: DO I = 1, M - P - Q
621: *
622: CALL ZSCAL( M-P-Q-I+1, DCMPLX( Z2*Z4, 0.0D0 ),
623: $ X22(P+I,Q+I), 1 )
624: CALL ZLARFGP( M-P-Q-I+1, X22(P+I,Q+I), X22(P+I+1,Q+I), 1,
625: $ TAUQ2(P+I) )
626: X22(P+I,Q+I) = ONE
627: *
628: CALL ZLARF( 'L', M-P-Q-I+1, M-P-Q-I, X22(P+I,Q+I), 1,
629: $ DCONJG(TAUQ2(P+I)), X22(P+I,Q+I+1), LDX22,
630: $ WORK )
631: *
632: END DO
633: *
634: END IF
635: *
636: RETURN
637: *
638: * End of ZUNBDB
639: *
640: END
641:
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