LAPACK 3.11.0
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
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.