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## zla_gbrcond_x()

double precision function zla_gbrcond_x | ( | character | trans,
|  | integer | n,
|  | integer | kl,
|  | integer | ku,
|  | complex*16, dimension( ldab, * ) | ab,
|  | integer | ldab,
|  | complex*16, dimension( ldafb, * ) | afb,
|  | integer | ldafb,
|  | integer, dimension( * ) | ipiv,
|  | complex*16, dimension( * ) | x,
|  | integer | info,
|  | complex*16, dimension( * ) | work,
|  | double precision, dimension( * ) | rwork )

ZLA_GBRCOND_X computes the infinity norm condition number of op(A)*diag(x) for general banded matrices.

Download ZLA_GBRCOND_X + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !>    ZLA_GBRCOND_X Computes the infinity norm condition number of
      !>    op(A) * diag(X) where X is a COMPLEX*16 vector.
      !>

Parameters

  [in]

  TRANS

      !>          TRANS is CHARACTER*1
      !>     Specifies the form of the system of equations:
      !>       = 'N':  A * X = B     (No transpose)
      !>       = 'T':  A**T * X = B  (Transpose)
      !>       = 'C':  A**H * X = B  (Conjugate Transpose = Transpose)
      !>

  [in]

  N

      !>          N is INTEGER
      !>     The number of linear equations, i.e., the order of the
      !>     matrix A.  N >= 0.
      !>

  [in]

  KL

      !>          KL is INTEGER
      !>     The number of subdiagonals within the band of A.  KL >= 0.
      !>

  [in]

  KU

      !>          KU is INTEGER
      !>     The number of superdiagonals within the band of A.  KU >= 0.
      !>

  [in]

  AB

      !>          AB is COMPLEX*16 array, dimension (LDAB,N)
      !>     On entry, the matrix A in band storage, in rows 1 to KL+KU+1.
      !>     The j-th column of A is stored in the j-th column of the
      !>     array AB as follows:
      !>     AB(KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+kl)
      !>

  [in]

  LDAB

      !>          LDAB is INTEGER
      !>     The leading dimension of the array AB.  LDAB >= KL+KU+1.
      !>

  [in]

  AFB

      !>          AFB is COMPLEX*16 array, dimension (LDAFB,N)
      !>     Details of the LU factorization of the band matrix A, as
      !>     computed by ZGBTRF.  U is stored as an upper triangular
      !>     band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1,
      !>     and the multipliers used during the factorization are stored
      !>     in rows KL+KU+2 to 2*KL+KU+1.
      !>

  [in]

  LDAFB

      !>          LDAFB is INTEGER
      !>     The leading dimension of the array AFB.  LDAFB >= 2*KL+KU+1.
      !>

  [in]

  IPIV

      !>          IPIV is INTEGER array, dimension (N)
      !>     The pivot indices from the factorization A = P*L*U
      !>     as computed by ZGBTRF; row i of the matrix was interchanged
      !>     with row IPIV(i).
      !>

  [in]

  X

      !>          X is COMPLEX*16 array, dimension (N)
      !>     The vector X in the formula op(A) * diag(X).
      !>

  [out]

  INFO

      !>          INFO is INTEGER
      !>       = 0:  Successful exit.
      !>     i > 0:  The ith argument is invalid.
      !>

  [out]

  WORK

      !>          WORK is COMPLEX*16 array, dimension (2*N).
      !>     Workspace.
      !>

  [out]

  RWORK

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

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