1       SUBROUTINE SCSDTS( M, P, Q, X, XF, LDX, U1, LDU1, U2, LDU2, V1T,
  2      $                   LDV1T, V2T, LDV2T, THETA, IWORK, WORK, LWORK,
  3      $                   RWORK, RESULT )
  4       IMPLICIT NONE
  5 *
  6 *     Originally xGSVTS
  7 *  -- LAPACK test routine (version 3.1) --
  8 *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
  9 *     November 2006
 10 *
 11 *     Adapted to SCSDTS
 12 *     July 2010
 13 *
 14 *     .. Scalar Arguments ..
 15       INTEGER            LDX, LDU1, LDU2, LDV1T, LDV2T, LWORK, M, P, Q
 16 *     ..
 17 *     .. Array Arguments ..
 18       INTEGER            IWORK( * )
 19       REAL               RESULT9 ), RWORK( * ), THETA( * )
 20       REAL               U1( LDU1, * ), U2( LDU2, * ), V1T( LDV1T, * ),
 21      $                   V2T( LDV2T, * ), WORK( LWORK ), X( LDX, * ),
 22      $                   XF( LDX, * )
 23 *     ..
 24 *
 25 *  Purpose
 26 *  =======
 27 *
 28 *  SCSDTS tests SORCSD, which, given an M-by-M partitioned orthogonal
 29 *  matrix X,
 30 *               Q  M-Q
 31 *        X = [ X11 X12 ] P   ,
 32 *            [ X21 X22 ] M-P
 33 *
 34 *  computes the CSD
 35 *
 36 *        [ U1    ]**T * [ X11 X12 ] * [ V1    ]
 37 *        [    U2 ]      [ X21 X22 ]   [    V2 ]
 38 *
 39 *                              [  I  0  0 |  0  0  0 ]
 40 *                              [  0  C  0 |  0 -S  0 ]
 41 *                              [  0  0  0 |  0  0 -I ]
 42 *                            = [---------------------] = [ D11 D12 ] .
 43 *                              [  0  0  0 |  I  0  0 ]   [ D21 D22 ]
 44 *                              [  0  S  0 |  0  C  0 ]
 45 *                              [  0  0  I |  0  0  0 ]
 46 *
 47 *  Arguments
 48 *  =========
 49 *
 50 *  M       (input) INTEGER
 51 *          The number of rows of the matrix X.  M >= 0.
 52 *
 53 *  P       (input) INTEGER
 54 *          The number of rows of the matrix X11.  P >= 0.
 55 *
 56 *  Q       (input) INTEGER
 57 *          The number of columns of the matrix X11.  Q >= 0.
 58 *
 59 *  X       (input) REAL array, dimension (LDX,M)
 60 *          The M-by-M matrix X.
 61 *
 62 *  XF      (output) REAL array, dimension (LDX,M)
 63 *          Details of the CSD of X, as returned by SORCSD;
 64 *          see SORCSD for further details.
 65 *
 66 *  LDX     (input) INTEGER
 67 *          The leading dimension of the arrays X and XF.
 68 *          LDX >= max( 1,M ).
 69 *
 70 *  U1      (output) REAL array, dimension(LDU1,P)
 71 *          The P-by-P orthogonal matrix U1.
 72 *
 73 *  LDU1    (input) INTEGER
 74 *          The leading dimension of the array U1. LDU >= max(1,P).
 75 *
 76 *  U2      (output) REAL array, dimension(LDU2,M-P)
 77 *          The (M-P)-by-(M-P) orthogonal matrix U2.
 78 *
 79 *  LDU2    (input) INTEGER
 80 *          The leading dimension of the array U2. LDU >= max(1,M-P).
 81 *
 82 *  V1T     (output) REAL array, dimension(LDV1T,Q)
 83 *          The Q-by-Q orthogonal matrix V1T.
 84 *
 85 *  LDV1T   (input) INTEGER
 86 *          The leading dimension of the array V1T. LDV1T >=
 87 *          max(1,Q).
 88 *
 89 *  V2T     (output) REAL array, dimension(LDV2T,M-Q)
 90 *          The (M-Q)-by-(M-Q) orthogonal matrix V2T.
 91 *
 92 *  LDV2T   (input) INTEGER
 93 *          The leading dimension of the array V2T. LDV2T >=
 94 *          max(1,M-Q).
 95 *
 96 *  THETA   (output) REAL array, dimension MIN(P,M-P,Q,M-Q)
 97 *          The CS values of X; the essentially diagonal matrices C and
 98 *          S are constructed from THETA; see subroutine SORCSD for
 99 *          details.
100 *
101 *  IWORK   (workspace) INTEGER array, dimension (M)
102 *
103 *  WORK    (workspace) REAL array, dimension (LWORK)
104 *
105 *  LWORK   (input) INTEGER
106 *          The dimension of the array WORK
107 *
108 *  RWORK   (workspace) REAL array
109 *
110 *  RESULT  (output) REAL array, dimension (9)
111 *          The test ratios:
112 *          RESULT(1) = norm( U1'*X11*V1 - D11 ) / ( MAX(1,P,Q)*EPS2 )
113 *          RESULT(2) = norm( U1'*X12*V2 - D12 ) / ( MAX(1,P,M-Q)*EPS2 )
114 *          RESULT(3) = norm( U2'*X21*V1 - D21 ) / ( MAX(1,M-P,Q)*EPS2 )
115 *          RESULT(4) = norm( U2'*X22*V2 - D22 ) / ( MAX(1,M-P,M-Q)*EPS2 )
116 *          RESULT(5) = norm( I - U1'*U1 ) / ( MAX(1,P)*ULP )
117 *          RESULT(6) = norm( I - U2'*U2 ) / ( MAX(1,M-P)*ULP )
118 *          RESULT(7) = norm( I - V1T'*V1T ) / ( MAX(1,Q)*ULP )
119 *          RESULT(8) = norm( I - V2T'*V2T ) / ( MAX(1,M-Q)*ULP )
120 *          RESULT(9) = 0        if THETA is in increasing order and
121 *                               all angles are in [0,pi/2];
122 *                    = ULPINV   otherwise.
123 *          ( EPS2 = MAX( norm( I - X'*X ) / M, ULP ). )
124 *
125 *  =====================================================================
126 *
127 *     .. Parameters ..
128       REAL               PIOVER2, REALONE, REALZERO
129       PARAMETER          ( PIOVER2 = 1.57079632679489662E0,
130      $                     REALONE = 1.0E0, REALZERO = 0.0E0 )
131       REAL               ZERO, ONE
132       PARAMETER          ( ZERO = 0.0E0, ONE = 1.0E0 )
133 *     ..
134 *     .. Local Scalars ..
135       INTEGER            I, INFO, R
136       REAL               EPS2, RESID, ULP, ULPINV
137 *     ..
138 *     .. External Functions ..
139       REAL               SLAMCH, SLANGE, SLANSY
140       EXTERNAL           SLAMCH, SLANGE, SLANSY
141 *     ..
142 *     .. External Subroutines ..
143       EXTERNAL           SGEMM, SLACPY, SLASET, SORCSD, SSYRK
144 *     ..
145 *     .. Intrinsic Functions ..
146       INTRINSIC          REAL, MAXMIN
147 *     ..
148 *     .. Executable Statements ..
149 *
150       ULP = SLAMCH( 'Precision' )
151       ULPINV = REALONE / ULP
152       CALL SLASET( 'Full', M, M, ZERO, ONE, WORK, LDX )
153       CALL SSYRK( 'Upper''Conjugate transpose', M, M, -ONE, X, LDX,
154      $            ONE, WORK, LDX )
155       EPS2 = MAX( ULP, 
156      $            SLANGE( '1', M, M, WORK, LDX, RWORK ) / REAL( M ) )
157       R = MIN( P, M-P, Q, M-Q )
158 *
159 *     Copy the matrix X to the array XF.
160 *
161       CALL SLACPY( 'Full', M, M, X, LDX, XF, LDX )
162 *
163 *     Compute the CSD
164 *
165       CALL SORCSD( 'Y''Y''Y''Y''N''D', M, P, Q, XF(1,1), LDX,
166      $             XF(1,Q+1), LDX, XF(P+1,1), LDX, XF(P+1,Q+1), LDX,
167      $             THETA, U1, LDU1, U2, LDU2, V1T, LDV1T, V2T, LDV2T,
168      $             WORK, LWORK, IWORK, INFO )
169 *
170 *     Compute X := diag(U1,U2)'*X*diag(V1,V2) - [D11 D12; D21 D22]
171 *
172       CALL SGEMM( 'No transpose''Conjugate transpose', P, Q, Q, ONE,
173      $            X, LDX, V1T, LDV1T, ZERO, WORK, LDX )
174 *
175       CALL SGEMM( 'Conjugate transpose''No transpose', P, Q, P, ONE,
176      $            U1, LDU1, WORK, LDX, ZERO, X, LDX )
177 *
178       DO I = 1MIN(P,Q)-R
179          X(I,I) = X(I,I) - ONE
180       END DO
181       DO I = 1, R
182          X(MIN(P,Q)-R+I,MIN(P,Q)-R+I) =
183      $           X(MIN(P,Q)-R+I,MIN(P,Q)-R+I) - COS(THETA(I))
184       END DO
185 *
186       CALL SGEMM( 'No transpose''Conjugate transpose', P, M-Q, M-Q,
187      $            ONE, X(1,Q+1), LDX, V2T, LDV2T, ZERO, WORK, LDX )
188 *
189       CALL SGEMM( 'Conjugate transpose''No transpose', P, M-Q, P,
190      $            ONE, U1, LDU1, WORK, LDX, ZERO, X(1,Q+1), LDX )
191 *
192       DO I = 1MIN(P,M-Q)-R
193          X(P-I+1,M-I+1= X(P-I+1,M-I+1+ ONE
194       END DO
195       DO I = 1, R
196          X(P-(MIN(P,M-Q)-R)+1-I,M-(MIN(P,M-Q)-R)+1-I) =
197      $      X(P-(MIN(P,M-Q)-R)+1-I,M-(MIN(P,M-Q)-R)+1-I) +
198      $      SIN(THETA(R-I+1))
199       END DO
200 *
201       CALL SGEMM( 'No transpose''Conjugate transpose', M-P, Q, Q, ONE,
202      $            X(P+1,1), LDX, V1T, LDV1T, ZERO, WORK, LDX )
203 *
204       CALL SGEMM( 'Conjugate transpose''No transpose', M-P, Q, M-P,
205      $            ONE, U2, LDU2, WORK, LDX, ZERO, X(P+1,1), LDX )
206 *
207       DO I = 1MIN(M-P,Q)-R
208          X(M-I+1,Q-I+1= X(M-I+1,Q-I+1- ONE
209       END DO
210       DO I = 1, R
211          X(M-(MIN(M-P,Q)-R)+1-I,Q-(MIN(M-P,Q)-R)+1-I) =
212      $             X(M-(MIN(M-P,Q)-R)+1-I,Q-(MIN(M-P,Q)-R)+1-I) -
213      $             SIN(THETA(R-I+1))
214       END DO
215 *
216       CALL SGEMM( 'No transpose''Conjugate transpose', M-P, M-Q, M-Q,
217      $            ONE, X(P+1,Q+1), LDX, V2T, LDV2T, ZERO, WORK, LDX )
218 *
219       CALL SGEMM( 'Conjugate transpose''No transpose', M-P, M-Q, M-P,
220      $            ONE, U2, LDU2, WORK, LDX, ZERO, X(P+1,Q+1), LDX )
221 *
222       DO I = 1MIN(M-P,M-Q)-R
223          X(P+I,Q+I) = X(P+I,Q+I) - ONE
224       END DO
225       DO I = 1, R
226          X(P+(MIN(M-P,M-Q)-R)+I,Q+(MIN(M-P,M-Q)-R)+I) =
227      $      X(P+(MIN(M-P,M-Q)-R)+I,Q+(MIN(M-P,M-Q)-R)+I) -
228      $      COS(THETA(I))
229       END DO
230 *
231 *     Compute norm( U1'*X11*V1 - D11 ) / ( MAX(1,P,Q)*EPS2 ) .
232 *
233       RESID = SLANGE( '1', P, Q, X, LDX, RWORK )
234       RESULT1 ) = ( RESID / REAL(MAX(1,P,Q)) ) / EPS2
235 *
236 *     Compute norm( U1'*X12*V2 - D12 ) / ( MAX(1,P,M-Q)*EPS2 ) .
237 *
238       RESID = SLANGE( '1', P, M-Q, X(1,Q+1), LDX, RWORK )
239       RESULT2 ) = ( RESID / REAL(MAX(1,P,M-Q)) ) / EPS2
240 *
241 *     Compute norm( U2'*X21*V1 - D21 ) / ( MAX(1,M-P,Q)*EPS2 ) .
242 *
243       RESID = SLANGE( '1', M-P, Q, X(P+1,1), LDX, RWORK )
244       RESULT3 ) = ( RESID / REAL(MAX(1,M-P,Q)) ) / EPS2
245 *
246 *     Compute norm( U2'*X22*V2 - D22 ) / ( MAX(1,M-P,M-Q)*EPS2 ) .
247 *
248       RESID = SLANGE( '1', M-P, M-Q, X(P+1,Q+1), LDX, RWORK )
249       RESULT4 ) = ( RESID / REAL(MAX(1,M-P,M-Q)) ) / EPS2
250 *
251 *     Compute I - U1'*U1
252 *
253       CALL SLASET( 'Full', P, P, ZERO, ONE, WORK, LDU1 )
254       CALL SSYRK( 'Upper''Conjugate transpose', P, P, -ONE, U1, LDU1,
255      $            ONE, WORK, LDU1 )
256 *
257 *     Compute norm( I - U'*U ) / ( MAX(1,P) * ULP ) .
258 *
259       RESID = SLANSY( '1''Upper', P, WORK, LDU1, RWORK )
260       RESULT5 ) = ( RESID / REAL(MAX(1,P)) ) / ULP
261 *
262 *     Compute I - U2'*U2
263 *
264       CALL SLASET( 'Full', M-P, M-P, ZERO, ONE, WORK, LDU2 )
265       CALL SSYRK( 'Upper''Conjugate transpose', M-P, M-P, -ONE, U2,
266      $            LDU2, ONE, WORK, LDU2 )
267 *
268 *     Compute norm( I - U2'*U2 ) / ( MAX(1,M-P) * ULP ) .
269 *
270       RESID = SLANSY( '1''Upper', M-P, WORK, LDU2, RWORK )
271       RESULT6 ) = ( RESID / REAL(MAX(1,M-P)) ) / ULP
272 *
273 *     Compute I - V1T*V1T'
274 *
275       CALL SLASET( 'Full', Q, Q, ZERO, ONE, WORK, LDV1T )
276       CALL SSYRK( 'Upper''No transpose', Q, Q, -ONE, V1T, LDV1T, ONE,
277      $            WORK, LDV1T )
278 *
279 *     Compute norm( I - V1T*V1T' ) / ( MAX(1,Q) * ULP ) .
280 *
281       RESID = SLANSY( '1''Upper', Q, WORK, LDV1T, RWORK )
282       RESULT7 ) = ( RESID / REAL(MAX(1,Q)) ) / ULP
283 *
284 *     Compute I - V2T*V2T'
285 *
286       CALL SLASET( 'Full', M-Q, M-Q, ZERO, ONE, WORK, LDV2T )
287       CALL SSYRK( 'Upper''No transpose', M-Q, M-Q, -ONE, V2T, LDV2T,
288      $            ONE, WORK, LDV2T )
289 *
290 *     Compute norm( I - V2T*V2T' ) / ( MAX(1,M-Q) * ULP ) .
291 *
292       RESID = SLANSY( '1''Upper', M-Q, WORK, LDV2T, RWORK )
293       RESULT8 ) = ( RESID / REAL(MAX(1,M-Q)) ) / ULP
294 *
295 *     Check sorting
296 *
297       RESULT(9= REALZERO
298       DO I = 1, R
299          IF( THETA(I).LT.REALZERO .OR. THETA(I).GT.PIOVER2 ) THEN
300             RESULT(9= ULPINV
301          END IF
302          IF( I.GT.1THEN
303             IF ( THETA(I).LT.THETA(I-1) ) THEN
304                RESULT(9= ULPINV
305             END IF
306          END IF
307       END DO
308 *
309       RETURN
310 *      
311 *     End of SCSDTS
312 *
313       END
314