LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 double precision function zla_syrcond_c ( character UPLO, integer N, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( ldaf, * ) AF, integer LDAF, integer, dimension( * ) IPIV, double precision, dimension( * ) C, logical CAPPLY, integer INFO, complex*16, dimension( * ) WORK, double precision, dimension( * ) RWORK )

ZLA_SYRCOND_C computes the infinity norm condition number of op(A)*inv(diag(c)) for symmetric indefinite matrices.

Purpose:
```    ZLA_SYRCOND_C Computes the infinity norm condition number of
op(A) * inv(diag(C)) where C is a DOUBLE PRECISION vector.```
Parameters
 [in] UPLO ``` UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.``` [in] N ``` N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.``` [in] A ``` A is COMPLEX*16 array, dimension (LDA,N) On entry, the N-by-N matrix A``` [in] LDA ``` LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).``` [in] AF ``` AF is COMPLEX*16 array, dimension (LDAF,N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ZSYTRF.``` [in] LDAF ``` LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).``` [in] IPIV ``` IPIV is INTEGER array, dimension (N) Details of the interchanges and the block structure of D as determined by ZSYTRF.``` [in] C ``` C is DOUBLE PRECISION array, dimension (N) The vector C in the formula op(A) * inv(diag(C)).``` [in] CAPPLY ``` CAPPLY is LOGICAL If .TRUE. then access the vector C in the formula above.``` [out] INFO ``` INFO is INTEGER = 0: Successful exit. i > 0: The ith argument is invalid.``` [in] WORK ``` WORK is COMPLEX*16 array, dimension (2*N). Workspace.``` [in] RWORK ``` RWORK is DOUBLE PRECISION array, dimension (N). Workspace.```
Date
September 2012

Definition at line 142 of file zla_syrcond_c.f.

142 *
143 * -- LAPACK computational routine (version 3.4.2) --
144 * -- LAPACK is a software package provided by Univ. of Tennessee, --
145 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
146 * September 2012
147 *
148 * .. Scalar Arguments ..
149  CHARACTER uplo
150  LOGICAL capply
151  INTEGER n, lda, ldaf, info
152 * ..
153 * .. Array Arguments ..
154  INTEGER ipiv( * )
155  COMPLEX*16 a( lda, * ), af( ldaf, * ), work( * )
156  DOUBLE PRECISION c( * ), rwork( * )
157 * ..
158 *
159 * =====================================================================
160 *
161 * .. Local Scalars ..
162  INTEGER kase
163  DOUBLE PRECISION ainvnm, anorm, tmp
164  INTEGER i, j
165  LOGICAL up, upper
166  COMPLEX*16 zdum
167 * ..
168 * .. Local Arrays ..
169  INTEGER isave( 3 )
170 * ..
171 * .. External Functions ..
172  LOGICAL lsame
173  EXTERNAL lsame
174 * ..
175 * .. External Subroutines ..
176  EXTERNAL zlacn2, zsytrs, xerbla
177 * ..
178 * .. Intrinsic Functions ..
179  INTRINSIC abs, max
180 * ..
181 * .. Statement Functions ..
182  DOUBLE PRECISION cabs1
183 * ..
184 * .. Statement Function Definitions ..
185  cabs1( zdum ) = abs( dble( zdum ) ) + abs( dimag( zdum ) )
186 * ..
187 * .. Executable Statements ..
188 *
189  zla_syrcond_c = 0.0d+0
190 *
191  info = 0
192  upper = lsame( uplo, 'U' )
193  IF( .NOT.upper .AND. .NOT.lsame( uplo, 'L' ) ) THEN
194  info = -1
195  ELSE IF( n.LT.0 ) THEN
196  info = -2
197  ELSE IF( lda.LT.max( 1, n ) ) THEN
198  info = -4
199  ELSE IF( ldaf.LT.max( 1, n ) ) THEN
200  info = -6
201  END IF
202  IF( info.NE.0 ) THEN
203  CALL xerbla( 'ZLA_SYRCOND_C', -info )
204  RETURN
205  END IF
206  up = .false.
207  IF ( lsame( uplo, 'U' ) ) up = .true.
208 *
209 * Compute norm of op(A)*op2(C).
210 *
211  anorm = 0.0d+0
212  IF ( up ) THEN
213  DO i = 1, n
214  tmp = 0.0d+0
215  IF ( capply ) THEN
216  DO j = 1, i
217  tmp = tmp + cabs1( a( j, i ) ) / c( j )
218  END DO
219  DO j = i+1, n
220  tmp = tmp + cabs1( a( i, j ) ) / c( j )
221  END DO
222  ELSE
223  DO j = 1, i
224  tmp = tmp + cabs1( a( j, i ) )
225  END DO
226  DO j = i+1, n
227  tmp = tmp + cabs1( a( i, j ) )
228  END DO
229  END IF
230  rwork( i ) = tmp
231  anorm = max( anorm, tmp )
232  END DO
233  ELSE
234  DO i = 1, n
235  tmp = 0.0d+0
236  IF ( capply ) THEN
237  DO j = 1, i
238  tmp = tmp + cabs1( a( i, j ) ) / c( j )
239  END DO
240  DO j = i+1, n
241  tmp = tmp + cabs1( a( j, i ) ) / c( j )
242  END DO
243  ELSE
244  DO j = 1, i
245  tmp = tmp + cabs1( a( i, j ) )
246  END DO
247  DO j = i+1, n
248  tmp = tmp + cabs1( a( j, i ) )
249  END DO
250  END IF
251  rwork( i ) = tmp
252  anorm = max( anorm, tmp )
253  END DO
254  END IF
255 *
256 * Quick return if possible.
257 *
258  IF( n.EQ.0 ) THEN
259  zla_syrcond_c = 1.0d+0
260  RETURN
261  ELSE IF( anorm .EQ. 0.0d+0 ) THEN
262  RETURN
263  END IF
264 *
265 * Estimate the norm of inv(op(A)).
266 *
267  ainvnm = 0.0d+0
268 *
269  kase = 0
270  10 CONTINUE
271  CALL zlacn2( n, work( n+1 ), work, ainvnm, kase, isave )
272  IF( kase.NE.0 ) THEN
273  IF( kase.EQ.2 ) THEN
274 *
275 * Multiply by R.
276 *
277  DO i = 1, n
278  work( i ) = work( i ) * rwork( i )
279  END DO
280 *
281  IF ( up ) THEN
282  CALL zsytrs( 'U', n, 1, af, ldaf, ipiv,
283  \$ work, n, info )
284  ELSE
285  CALL zsytrs( 'L', n, 1, af, ldaf, ipiv,
286  \$ work, n, info )
287  ENDIF
288 *
289 * Multiply by inv(C).
290 *
291  IF ( capply ) THEN
292  DO i = 1, n
293  work( i ) = work( i ) * c( i )
294  END DO
295  END IF
296  ELSE
297 *
298 * Multiply by inv(C**T).
299 *
300  IF ( capply ) THEN
301  DO i = 1, n
302  work( i ) = work( i ) * c( i )
303  END DO
304  END IF
305 *
306  IF ( up ) THEN
307  CALL zsytrs( 'U', n, 1, af, ldaf, ipiv,
308  \$ work, n, info )
309  ELSE
310  CALL zsytrs( 'L', n, 1, af, ldaf, ipiv,
311  \$ work, n, info )
312  END IF
313 *
314 * Multiply by R.
315 *
316  DO i = 1, n
317  work( i ) = work( i ) * rwork( i )
318  END DO
319  END IF
320  GO TO 10
321  END IF
322 *
323 * Compute the estimate of the reciprocal condition number.
324 *
325  IF( ainvnm .NE. 0.0d+0 )
326  \$ zla_syrcond_c = 1.0d+0 / ainvnm
327 *
328  RETURN
329 *
subroutine xerbla(SRNAME, INFO)
XERBLA
Definition: xerbla.f:62
double precision function zla_syrcond_c(UPLO, N, A, LDA, AF, LDAF, IPIV, C, CAPPLY, INFO, WORK, RWORK)
ZLA_SYRCOND_C computes the infinity norm condition number of op(A)*inv(diag(c)) for symmetric indefin...
subroutine zlacn2(N, V, X, EST, KASE, ISAVE)
ZLACN2 estimates the 1-norm of a square matrix, using reverse communication for evaluating matrix-vec...
Definition: zlacn2.f:135
subroutine zsytrs(UPLO, N, NRHS, A, LDA, IPIV, B, LDB, INFO)
ZSYTRS
Definition: zsytrs.f:122
logical function lsame(CA, CB)
LSAME
Definition: lsame.f:55

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