LAPACK  3.4.2
LAPACK: Linear Algebra PACKage
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cpbcon.f File Reference

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subroutine cpbcon (UPLO, N, KD, AB, LDAB, ANORM, RCOND, WORK, RWORK, INFO)

Function/Subroutine Documentation

subroutine cpbcon ( character  UPLO,
integer  N,
integer  KD,
complex, dimension( ldab, * )  AB,
integer  LDAB,
real  ANORM,
real  RCOND,
complex, dimension( * )  WORK,
real, dimension( * )  RWORK,
integer  INFO 


Download CPBCON + dependencies [TGZ] [ZIP] [TXT]
 CPBCON estimates the reciprocal of the condition number (in the
 1-norm) of a complex Hermitian positive definite band matrix using
 the Cholesky factorization A = U**H*U or A = L*L**H computed by

 An estimate is obtained for norm(inv(A)), and the reciprocal of the
 condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
          UPLO is CHARACTER*1
          = 'U':  Upper triangular factor stored in AB;
          = 'L':  Lower triangular factor stored in AB.
          N is INTEGER
          The order of the matrix A.  N >= 0.
          KD is INTEGER
          The number of superdiagonals of the matrix A if UPLO = 'U',
          or the number of sub-diagonals if UPLO = 'L'.  KD >= 0.
          AB is COMPLEX array, dimension (LDAB,N)
          The triangular factor U or L from the Cholesky factorization
          A = U**H*U or A = L*L**H of the band matrix A, stored in the
          first KD+1 rows of the array.  The j-th column of U or L is
          stored in the j-th column of the array AB as follows:
          if UPLO ='U', AB(kd+1+i-j,j) = U(i,j) for max(1,j-kd)<=i<=j;
          if UPLO ='L', AB(1+i-j,j)    = L(i,j) for j<=i<=min(n,j+kd).
          LDAB is INTEGER
          The leading dimension of the array AB.  LDAB >= KD+1.
          ANORM is REAL
          The 1-norm (or infinity-norm) of the Hermitian band matrix A.
          RCOND is REAL
          The reciprocal of the condition number of the matrix A,
          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
          estimate of the 1-norm of inv(A) computed in this routine.
          WORK is COMPLEX array, dimension (2*N)
          RWORK is REAL array, dimension (N)
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
November 2011

Definition at line 133 of file cpbcon.f.

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