cgbt01.f - Man Page

TESTING/LIN/cgbt01.f

Synopsis

Functions/Subroutines

subroutine cgbt01 (m, n, kl, ku, a, lda, afac, ldafac, ipiv, work, resid)
CGBT01

Function/Subroutine Documentation

subroutine cgbt01 (integer m, integer n, integer kl, integer ku, complex, dimension( lda, * ) a, integer lda, complex, dimension( ldafac, * ) afac, integer ldafac, integer, dimension( * ) ipiv, complex, dimension( * ) work, real resid)

CGBT01

Purpose:

 CGBT01 reconstructs a band matrix A from its L*U factorization and
 computes the residual:
    norm(L*U - A) / ( N * norm(A) * EPS ),
 where EPS is the machine epsilon.

 The expression L*U - A is computed one column at a time, so A and
 AFAC are not modified.
Parameters

M

          M is INTEGER
          The number of rows of the matrix A.  M >= 0.

N

          N is INTEGER
          The number of columns of the matrix A.  N >= 0.

KL

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

KU

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

A

          A is COMPLEX array, dimension (LDA,N)
          The original matrix A in band storage, stored in rows 1 to
          KL+KU+1.

LDA

          LDA is INTEGER.
          The leading dimension of the array A.  LDA >= max(1,KL+KU+1).

AFAC

          AFAC is COMPLEX array, dimension (LDAFAC,N)
          The factored form of the matrix A.  AFAC contains the banded
          factors L and U from the L*U factorization, as computed by
          CGBTRF.  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.  See CGBTRF for further details.

LDAFAC

          LDAFAC is INTEGER
          The leading dimension of the array AFAC.
          LDAFAC >= max(1,2*KL*KU+1).

IPIV

          IPIV is INTEGER array, dimension (min(M,N))
          The pivot indices from CGBTRF.

WORK

          WORK is COMPLEX array, dimension (2*KL+KU+1)

RESID

          RESID is REAL
          norm(L*U - A) / ( N * norm(A) * EPS )
Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 124 of file cgbt01.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page cgbt01(3) is an alias of cgbt01.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK