 LAPACK  3.10.1 LAPACK: Linear Algebra PACKage

## ◆ cget22()

 subroutine cget22 ( character TRANSA, character TRANSE, character TRANSW, integer N, complex, dimension( lda, * ) A, integer LDA, complex, dimension( lde, * ) E, integer LDE, complex, dimension( * ) W, complex, dimension( * ) WORK, real, dimension( * ) RWORK, real, dimension( 2 ) RESULT )

CGET22

Purpose:
``` CGET22 does an eigenvector check.

The basic test is:

RESULT(1) = | A E  -  E W | / ( |A| |E| ulp )

using the 1-norm.  It also tests the normalization of E:

RESULT(2) = max | m-norm(E(j)) - 1 | / ( n ulp )
j

where E(j) is the j-th eigenvector, and m-norm is the max-norm of a
vector.  The max-norm of a complex n-vector x in this case is the
maximum of |re(x(i)| + |im(x(i)| over i = 1, ..., n.```
Parameters
 [in] TRANSA ``` TRANSA is CHARACTER*1 Specifies whether or not A is transposed. = 'N': No transpose = 'T': Transpose = 'C': Conjugate transpose``` [in] TRANSE ``` TRANSE is CHARACTER*1 Specifies whether or not E is transposed. = 'N': No transpose, eigenvectors are in columns of E = 'T': Transpose, eigenvectors are in rows of E = 'C': Conjugate transpose, eigenvectors are in rows of E``` [in] TRANSW ``` TRANSW is CHARACTER*1 Specifies whether or not W is transposed. = 'N': No transpose = 'T': Transpose, same as TRANSW = 'N' = 'C': Conjugate transpose, use -WI(j) instead of WI(j)``` [in] N ``` N is INTEGER The order of the matrix A. N >= 0.``` [in] A ``` A is COMPLEX array, dimension (LDA,N) The matrix whose eigenvectors are in E.``` [in] LDA ``` LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).``` [in] E ``` E is COMPLEX array, dimension (LDE,N) The matrix of eigenvectors. If TRANSE = 'N', the eigenvectors are stored in the columns of E, if TRANSE = 'T' or 'C', the eigenvectors are stored in the rows of E.``` [in] LDE ``` LDE is INTEGER The leading dimension of the array E. LDE >= max(1,N).``` [in] W ``` W is COMPLEX array, dimension (N) The eigenvalues of A.``` [out] WORK ` WORK is COMPLEX array, dimension (N*N)` [out] RWORK ` RWORK is REAL array, dimension (N)` [out] RESULT ``` RESULT is REAL array, dimension (2) RESULT(1) = | A E - E W | / ( |A| |E| ulp ) RESULT(2) = max | m-norm(E(j)) - 1 | / ( n ulp ) j```

Definition at line 142 of file cget22.f.

144 *
145 * -- LAPACK test routine --
146 * -- LAPACK is a software package provided by Univ. of Tennessee, --
147 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
148 *
149 * .. Scalar Arguments ..
150  CHARACTER TRANSA, TRANSE, TRANSW
151  INTEGER LDA, LDE, N
152 * ..
153 * .. Array Arguments ..
154  REAL RESULT( 2 ), RWORK( * )
155  COMPLEX A( LDA, * ), E( LDE, * ), W( * ), WORK( * )
156 * ..
157 *
158 * =====================================================================
159 *
160 * .. Parameters ..
161  REAL ZERO, ONE
162  parameter( zero = 0.0e+0, one = 1.0e+0 )
163  COMPLEX CZERO, CONE
164  parameter( czero = ( 0.0e+0, 0.0e+0 ),
165  \$ cone = ( 1.0e+0, 0.0e+0 ) )
166 * ..
167 * .. Local Scalars ..
168  CHARACTER NORMA, NORME
169  INTEGER ITRNSE, ITRNSW, J, JCOL, JOFF, JROW, JVEC
170  REAL ANORM, ENORM, ENRMAX, ENRMIN, ERRNRM, TEMP1,
171  \$ ULP, UNFL
172  COMPLEX WTEMP
173 * ..
174 * .. External Functions ..
175  LOGICAL LSAME
176  REAL CLANGE, SLAMCH
177  EXTERNAL lsame, clange, slamch
178 * ..
179 * .. External Subroutines ..
180  EXTERNAL cgemm, claset
181 * ..
182 * .. Intrinsic Functions ..
183  INTRINSIC abs, aimag, conjg, max, min, real
184 * ..
185 * .. Executable Statements ..
186 *
187 * Initialize RESULT (in case N=0)
188 *
189  result( 1 ) = zero
190  result( 2 ) = zero
191  IF( n.LE.0 )
192  \$ RETURN
193 *
194  unfl = slamch( 'Safe minimum' )
195  ulp = slamch( 'Precision' )
196 *
197  itrnse = 0
198  itrnsw = 0
199  norma = 'O'
200  norme = 'O'
201 *
202  IF( lsame( transa, 'T' ) .OR. lsame( transa, 'C' ) ) THEN
203  norma = 'I'
204  END IF
205 *
206  IF( lsame( transe, 'T' ) ) THEN
207  itrnse = 1
208  norme = 'I'
209  ELSE IF( lsame( transe, 'C' ) ) THEN
210  itrnse = 2
211  norme = 'I'
212  END IF
213 *
214  IF( lsame( transw, 'C' ) ) THEN
215  itrnsw = 1
216  END IF
217 *
218 * Normalization of E:
219 *
220  enrmin = one / ulp
221  enrmax = zero
222  IF( itrnse.EQ.0 ) THEN
223  DO 20 jvec = 1, n
224  temp1 = zero
225  DO 10 j = 1, n
226  temp1 = max( temp1, abs( real( e( j, jvec ) ) )+
227  \$ abs( aimag( e( j, jvec ) ) ) )
228  10 CONTINUE
229  enrmin = min( enrmin, temp1 )
230  enrmax = max( enrmax, temp1 )
231  20 CONTINUE
232  ELSE
233  DO 30 jvec = 1, n
234  rwork( jvec ) = zero
235  30 CONTINUE
236 *
237  DO 50 j = 1, n
238  DO 40 jvec = 1, n
239  rwork( jvec ) = max( rwork( jvec ),
240  \$ abs( real( e( jvec, j ) ) )+
241  \$ abs( aimag( e( jvec, j ) ) ) )
242  40 CONTINUE
243  50 CONTINUE
244 *
245  DO 60 jvec = 1, n
246  enrmin = min( enrmin, rwork( jvec ) )
247  enrmax = max( enrmax, rwork( jvec ) )
248  60 CONTINUE
249  END IF
250 *
251 * Norm of A:
252 *
253  anorm = max( clange( norma, n, n, a, lda, rwork ), unfl )
254 *
255 * Norm of E:
256 *
257  enorm = max( clange( norme, n, n, e, lde, rwork ), ulp )
258 *
259 * Norm of error:
260 *
261 * Error = AE - EW
262 *
263  CALL claset( 'Full', n, n, czero, czero, work, n )
264 *
265  joff = 0
266  DO 100 jcol = 1, n
267  IF( itrnsw.EQ.0 ) THEN
268  wtemp = w( jcol )
269  ELSE
270  wtemp = conjg( w( jcol ) )
271  END IF
272 *
273  IF( itrnse.EQ.0 ) THEN
274  DO 70 jrow = 1, n
275  work( joff+jrow ) = e( jrow, jcol )*wtemp
276  70 CONTINUE
277  ELSE IF( itrnse.EQ.1 ) THEN
278  DO 80 jrow = 1, n
279  work( joff+jrow ) = e( jcol, jrow )*wtemp
280  80 CONTINUE
281  ELSE
282  DO 90 jrow = 1, n
283  work( joff+jrow ) = conjg( e( jcol, jrow ) )*wtemp
284  90 CONTINUE
285  END IF
286  joff = joff + n
287  100 CONTINUE
288 *
289  CALL cgemm( transa, transe, n, n, n, cone, a, lda, e, lde, -cone,
290  \$ work, n )
291 *
292  errnrm = clange( 'One', n, n, work, n, rwork ) / enorm
293 *
294 * Compute RESULT(1) (avoiding under/overflow)
295 *
296  IF( anorm.GT.errnrm ) THEN
297  result( 1 ) = ( errnrm / anorm ) / ulp
298  ELSE
299  IF( anorm.LT.one ) THEN
300  result( 1 ) = one / ulp
301  ELSE
302  result( 1 ) = min( errnrm / anorm, one ) / ulp
303  END IF
304  END IF
305 *
306 * Compute RESULT(2) : the normalization error in E.
307 *
308  result( 2 ) = max( abs( enrmax-one ), abs( enrmin-one ) ) /
309  \$ ( real( n )*ulp )
310 *
311  RETURN
312 *
313 * End of CGET22
314 *
logical function lde(RI, RJ, LR)
Definition: dblat2.f:2942
logical function lsame(CA, CB)
LSAME
Definition: lsame.f:53
subroutine cgemm(TRANSA, TRANSB, M, N, K, ALPHA, A, LDA, B, LDB, BETA, C, LDC)
CGEMM
Definition: cgemm.f:187
real function clange(NORM, M, N, A, LDA, WORK)
CLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition: clange.f:115
subroutine claset(UPLO, M, N, ALPHA, BETA, A, LDA)
CLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values.
Definition: claset.f:106
real function slamch(CMACH)
SLAMCH
Definition: slamch.f:68
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