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zla_gbrpvgrw.f(3) LAPACK zla_gbrpvgrw.f(3)

zla_gbrpvgrw.f -


DOUBLE PRECISION function zla_gbrpvgrw (N, KL, KU, NCOLS, AB, LDAB, AFB, LDAFB)
 
ZLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.

ZLA_GBRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a general banded matrix.
Purpose:
 ZLA_GBRPVGRW computes the reciprocal pivot growth factor
 norm(A)/norm(U). The "max absolute element" norm is used. If this is
 much less than 1, the stability of the LU factorization of the
 (equilibrated) matrix A could be poor. This also means that the
 solution X, estimated condition numbers, and error bounds could be
 unreliable.
Parameters:
N
          N is INTEGER
     The number of linear equations, i.e., the order 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.
NCOLS
          NCOLS is INTEGER
     The number of columns of the matrix A.  NCOLS >= 0.
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)
LDAB
          LDAB is INTEGER
     The leading dimension of the array AB.  LDAB >= KL+KU+1.
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.
LDAFB
          LDAFB is INTEGER
     The leading dimension of the array AFB.  LDAFB >= 2*KL+KU+1.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 117 of file zla_gbrpvgrw.f.

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Sat Nov 16 2013 Version 3.4.2

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