LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
|
subroutine zpbcon | ( | character | UPLO, |
integer | N, | ||
integer | KD, | ||
complex*16, dimension( ldab, * ) | AB, | ||
integer | LDAB, | ||
double precision | ANORM, | ||
double precision | RCOND, | ||
complex*16, dimension( * ) | WORK, | ||
double precision, dimension( * ) | RWORK, | ||
integer | INFO | ||
) |
ZPBCON
Download ZPBCON + dependencies [TGZ] [ZIP] [TXT]
ZPBCON 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 ZPBTRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
[in] | UPLO | UPLO is CHARACTER*1 = 'U': Upper triangular factor stored in AB; = 'L': Lower triangular factor stored in AB. |
[in] | N | N is INTEGER The order of the matrix A. N >= 0. |
[in] | KD | 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. |
[in] | AB | AB is COMPLEX*16 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). |
[in] | LDAB | LDAB is INTEGER The leading dimension of the array AB. LDAB >= KD+1. |
[in] | ANORM | ANORM is DOUBLE PRECISION The 1-norm (or infinity-norm) of the Hermitian band matrix A. |
[out] | RCOND | RCOND is DOUBLE PRECISION 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. |
[out] | WORK | WORK is COMPLEX*16 array, dimension (2*N) |
[out] | RWORK | RWORK is DOUBLE PRECISION array, dimension (N) |
[out] | INFO | INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value |
Definition at line 135 of file zpbcon.f.