LAPACK 3.12.1
LAPACK: Linear Algebra PACKage
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◆ zget52()

subroutine zget52 ( logical left,
integer n,
complex*16, dimension( lda, * ) a,
integer lda,
complex*16, dimension( ldb, * ) b,
integer ldb,
complex*16, dimension( lde, * ) e,
integer lde,
complex*16, dimension( * ) alpha,
complex*16, dimension( * ) beta,
complex*16, dimension( * ) work,
double precision, dimension( * ) rwork,
double precision, dimension( 2 ) result )

ZGET52

Purpose:
!>
!> ZGET52  does an eigenvector check for the generalized eigenvalue
!> problem.
!>
!> The basic test for right eigenvectors is:
!>
!>                           | b(i) A E(i) -  a(i) B E(i) |
!>         RESULT(1) = max   -------------------------------
!>                      i    n ulp max( |b(i) A|, |a(i) B| )
!>
!> using the 1-norm.  Here, a(i)/b(i) = w is the i-th generalized
!> eigenvalue of A - w B, or, equivalently, b(i)/a(i) = m is the i-th
!> generalized eigenvalue of m A - B.
!>
!>                         H   H  _      _
!> For left eigenvectors, A , B , a, and b  are used.
!>
!> ZGET52 also tests the normalization of E.  Each eigenvector is
!> supposed to be normalized so that the maximum 
!> of its elements is 1, where in this case, 
!> of a complex value x is  |Re(x)| + |Im(x)| ; let us call this
!> maximum  norm of a vector v  M(v).
!> If a(i)=b(i)=0, then the eigenvector is set to be the jth coordinate
!> vector. The normalization test is:
!>
!>         RESULT(2) =      max       | M(v(i)) - 1 | / ( n ulp )
!>                    eigenvectors v(i)
!>
!>
Parameters
[in]LEFT
!>          LEFT is LOGICAL
!>          =.TRUE.:  The eigenvectors in the columns of E are assumed
!>                    to be *left* eigenvectors.
!>          =.FALSE.: The eigenvectors in the columns of E are assumed
!>                    to be *right* eigenvectors.
!>
[in]N
!>          N is INTEGER
!>          The size of the matrices.  If it is zero, ZGET52 does
!>          nothing.  It must be at least zero.
!>
[in]A
!>          A is COMPLEX*16 array, dimension (LDA, N)
!>          The matrix A.
!>
[in]LDA
!>          LDA is INTEGER
!>          The leading dimension of A.  It must be at least 1
!>          and at least N.
!>
[in]B
!>          B is COMPLEX*16 array, dimension (LDB, N)
!>          The matrix B.
!>
[in]LDB
!>          LDB is INTEGER
!>          The leading dimension of B.  It must be at least 1
!>          and at least N.
!>
[in]E
!>          E is COMPLEX*16 array, dimension (LDE, N)
!>          The matrix of eigenvectors.  It must be O( 1 ).
!>
[in]LDE
!>          LDE is INTEGER
!>          The leading dimension of E.  It must be at least 1 and at
!>          least N.
!>
[in]ALPHA
!>          ALPHA is COMPLEX*16 array, dimension (N)
!>          The values a(i) as described above, which, along with b(i),
!>          define the generalized eigenvalues.
!>
[in]BETA
!>          BETA is COMPLEX*16 array, dimension (N)
!>          The values b(i) as described above, which, along with a(i),
!>          define the generalized eigenvalues.
!>
[out]WORK
!>          WORK is COMPLEX*16 array, dimension (N**2)
!>
[out]RWORK
!>          RWORK is DOUBLE PRECISION array, dimension (N)
!>
[out]RESULT
!>          RESULT is DOUBLE PRECISION array, dimension (2)
!>          The values computed by the test described above.  If A E or
!>          B E is likely to overflow, then RESULT(1:2) is set to
!>          10 / ulp.
!>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.

Definition at line 160 of file zget52.f.

162*
163* -- LAPACK test routine --
164* -- LAPACK is a software package provided by Univ. of Tennessee, --
165* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
166*
167* .. Scalar Arguments ..
168 LOGICAL LEFT
169 INTEGER LDA, LDB, LDE, N
170* ..
171* .. Array Arguments ..
172 DOUBLE PRECISION RESULT( 2 ), RWORK( * )
173 COMPLEX*16 A( LDA, * ), ALPHA( * ), B( LDB, * ),
174 $ BETA( * ), E( LDE, * ), WORK( * )
175* ..
176*
177* =====================================================================
178*
179* .. Parameters ..
180 DOUBLE PRECISION ZERO, ONE
181 parameter( zero = 0.0d+0, one = 1.0d+0 )
182 COMPLEX*16 CZERO, CONE
183 parameter( czero = ( 0.0d+0, 0.0d+0 ),
184 $ cone = ( 1.0d+0, 0.0d+0 ) )
185* ..
186* .. Local Scalars ..
187 CHARACTER NORMAB, TRANS
188 INTEGER J, JVEC
189 DOUBLE PRECISION ABMAX, ALFMAX, ANORM, BETMAX, BNORM, ENORM,
190 $ ENRMER, ERRNRM, SAFMAX, SAFMIN, SCALE, TEMP1,
191 $ ULP
192 COMPLEX*16 ACOEFF, ALPHAI, BCOEFF, BETAI, X
193* ..
194* .. External Functions ..
195 DOUBLE PRECISION DLAMCH, ZLANGE
196 EXTERNAL dlamch, zlange
197* ..
198* .. External Subroutines ..
199 EXTERNAL zgemv
200* ..
201* .. Intrinsic Functions ..
202 INTRINSIC abs, dble, dconjg, dimag, max
203* ..
204* .. Statement Functions ..
205 DOUBLE PRECISION ABS1
206* ..
207* .. Statement Function definitions ..
208 abs1( x ) = abs( dble( x ) ) + abs( dimag( x ) )
209* ..
210* .. Executable Statements ..
211*
212 result( 1 ) = zero
213 result( 2 ) = zero
214 IF( n.LE.0 )
215 $ RETURN
216*
217 safmin = dlamch( 'Safe minimum' )
218 safmax = one / safmin
219 ulp = dlamch( 'Epsilon' )*dlamch( 'Base' )
220*
221 IF( left ) THEN
222 trans = 'C'
223 normab = 'I'
224 ELSE
225 trans = 'N'
226 normab = 'O'
227 END IF
228*
229* Norm of A, B, and E:
230*
231 anorm = max( zlange( normab, n, n, a, lda, rwork ), safmin )
232 bnorm = max( zlange( normab, n, n, b, ldb, rwork ), safmin )
233 enorm = max( zlange( 'O', n, n, e, lde, rwork ), ulp )
234 alfmax = safmax / max( one, bnorm )
235 betmax = safmax / max( one, anorm )
236*
237* Compute error matrix.
238* Column i = ( b(i) A - a(i) B ) E(i) / max( |a(i) B|, |b(i) A| )
239*
240 DO 10 jvec = 1, n
241 alphai = alpha( jvec )
242 betai = beta( jvec )
243 abmax = max( abs1( alphai ), abs1( betai ) )
244 IF( abs1( alphai ).GT.alfmax .OR. abs1( betai ).GT.betmax .OR.
245 $ abmax.LT.one ) THEN
246 scale = one / max( abmax, safmin )
247 alphai = scale*alphai
248 betai = scale*betai
249 END IF
250 scale = one / max( abs1( alphai )*bnorm, abs1( betai )*anorm,
251 $ safmin )
252 acoeff = scale*betai
253 bcoeff = scale*alphai
254 IF( left ) THEN
255 acoeff = dconjg( acoeff )
256 bcoeff = dconjg( bcoeff )
257 END IF
258 CALL zgemv( trans, n, n, acoeff, a, lda, e( 1, jvec ), 1,
259 $ czero, work( n*( jvec-1 )+1 ), 1 )
260 CALL zgemv( trans, n, n, -bcoeff, b, ldb, e( 1, jvec ), 1,
261 $ cone, work( n*( jvec-1 )+1 ), 1 )
262 10 CONTINUE
263*
264 errnrm = zlange( 'One', n, n, work, n, rwork ) / enorm
265*
266* Compute RESULT(1)
267*
268 result( 1 ) = errnrm / ulp
269*
270* Normalization of E:
271*
272 enrmer = zero
273 DO 30 jvec = 1, n
274 temp1 = zero
275 DO 20 j = 1, n
276 temp1 = max( temp1, abs1( e( j, jvec ) ) )
277 20 CONTINUE
278 enrmer = max( enrmer, abs( temp1-one ) )
279 30 CONTINUE
280*
281* Compute RESULT(2) : the normalization error in E.
282*
283 result( 2 ) = enrmer / ( dble( n )*ulp )
284*
285 RETURN
286*
287* End of ZGET52
288*
lde
logical function lde(ri, rj, lr)
Definition dblat2.f:2970
zgemv
subroutine zgemv(trans, m, n, alpha, a, lda, x, incx, beta, y, incy)
ZGEMV
Definition zgemv.f:160
dlamch
double precision function dlamch(cmach)
DLAMCH
Definition dlamch.f:69
zlange
double precision function zlange(norm, m, n, a, lda, work)
ZLANGE returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value ...
Definition zlange.f:113
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