TESTING/EIG/zstt22.f(3)    Library Functions Manual    TESTING/EIG/zstt22.f(3)

NAME
       TESTING/EIG/zstt22.f

SYNOPSIS
   Functions/Subroutines
       subroutine zstt22 (n, m, kband, ad, ae, sd, se, u, ldu, work, ldwork,
           rwork, result)
           ZSTT22

Function/Subroutine Documentation
   subroutine zstt22 (integer n, integer m, integer kband, double precision,
       dimension( * ) ad, double precision, dimension( * ) ae, double
       precision, dimension( * ) sd, double precision, dimension( * ) se,
       complex*16, dimension( ldu, * ) u, integer ldu, complex*16, dimension(
       ldwork, * ) work, integer ldwork, double precision, dimension( * )
       rwork, double precision, dimension( 2 ) result)
       ZSTT22

       Purpose:


           !>
           !> ZSTT22  checks a set of M eigenvalues and eigenvectors,
           !>
           !>     A U = U S
           !>
           !> where A is Hermitian tridiagonal, the columns of U are unitary,
           !> and S is diagonal (if KBAND=0) or Hermitian tridiagonal (if KBAND=1).
           !> Two tests are performed:
           !>
           !>    RESULT(1) = | U* A U - S | / ( |A| m ulp )
           !>
           !>    RESULT(2) = | I - U*U | / ( m ulp )
           !>

       Parameters
           N

           !>          N is INTEGER
           !>          The size of the matrix.  If it is zero, ZSTT22 does nothing.
           !>          It must be at least zero.
           !>

           M

           !>          M is INTEGER
           !>          The number of eigenpairs to check.  If it is zero, ZSTT22
           !>          does nothing.  It must be at least zero.
           !>

           KBAND

           !>          KBAND is INTEGER
           !>          The bandwidth of the matrix S.  It may only be zero or one.
           !>          If zero, then S is diagonal, and SE is not referenced.  If
           !>          one, then S is Hermitian tri-diagonal.
           !>

           AD

           !>          AD is DOUBLE PRECISION array, dimension (N)
           !>          The diagonal of the original (unfactored) matrix A.  A is
           !>          assumed to be Hermitian tridiagonal.
           !>

           AE

           !>          AE is DOUBLE PRECISION array, dimension (N)
           !>          The off-diagonal of the original (unfactored) matrix A.  A
           !>          is assumed to be Hermitian tridiagonal.  AE(1) is ignored,
           !>          AE(2) is the (1,2) and (2,1) element, etc.
           !>

           SD

           !>          SD is DOUBLE PRECISION array, dimension (N)
           !>          The diagonal of the (Hermitian tri-) diagonal matrix S.
           !>

           SE

           !>          SE is DOUBLE PRECISION array, dimension (N)
           !>          The off-diagonal of the (Hermitian tri-) diagonal matrix S.
           !>          Not referenced if KBSND=0.  If KBAND=1, then AE(1) is
           !>          ignored, SE(2) is the (1,2) and (2,1) element, etc.
           !>

           U

           !>          U is DOUBLE PRECISION array, dimension (LDU, N)
           !>          The unitary matrix in the decomposition.
           !>

           LDU

           !>          LDU is INTEGER
           !>          The leading dimension of U.  LDU must be at least N.
           !>

           WORK

           !>          WORK is COMPLEX*16 array, dimension (LDWORK, M+1)
           !>

           LDWORK

           !>          LDWORK is INTEGER
           !>          The leading dimension of WORK.  LDWORK must be at least
           !>          max(1,M).
           !>

           RWORK

           !>          RWORK is DOUBLE PRECISION array, dimension (N)
           !>

           RESULT

           !>          RESULT is DOUBLE PRECISION array, dimension (2)
           !>          The values computed by the two tests described above.  The
           !>          values are currently limited to 1/ulp, to avoid overflow.
           !>

       Author
           Univ. of Tennessee


           Univ. of California Berkeley


           Univ. of Colorado Denver


           NAG Ltd.

       Definition at line 143 of file zstt22.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/EIG/zstt22.f(3)