table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zhbtrd.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zhbtrd.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/zhbtrd.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine ZHBTRD (vect, uplo, n, kd, ab, ldab, d, e, q,
ldq, work, info)
ZHBTRD
Function/Subroutine Documentation¶
subroutine ZHBTRD (character vect, character uplo, integer n, integer kd, complex*16, dimension( ldab, * ) ab, integer ldab, double precision, dimension( * ) d, double precision, dimension( * ) e, complex*16, dimension( ldq, * ) q, integer ldq, complex*16, dimension( * ) work, integer info)¶
ZHBTRD
Purpose:
!> !> ZHBTRD reduces a complex Hermitian band matrix A to real symmetric !> tridiagonal form T by a unitary similarity transformation: !> Q**H * A * Q = T. !>
Parameters
VECT
!> VECT is CHARACTER*1 !> = 'N': do not form Q; !> = 'V': form Q; !> = 'U': update a matrix X, by forming X*Q. !>
UPLO
!> UPLO is CHARACTER*1 !> = 'U': Upper triangle of A is stored; !> = 'L': Lower triangle of A is stored. !>
N
!> N is INTEGER !> The order of the matrix A. N >= 0. !>
KD
!> KD is INTEGER !> The number of superdiagonals of the matrix A if UPLO = 'U', !> or the number of subdiagonals if UPLO = 'L'. KD >= 0. !>
AB
!> AB is COMPLEX*16 array, dimension (LDAB,N) !> On entry, the upper or lower triangle of the Hermitian band !> matrix A, stored in the first KD+1 rows of the array. The !> j-th column of A is stored in the j-th column of the array AB !> as follows: !> if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; !> if UPLO = 'L', AB(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd). !> On exit, the diagonal elements of AB are overwritten by the !> diagonal elements of the tridiagonal matrix T; if KD > 0, the !> elements on the first superdiagonal (if UPLO = 'U') or the !> first subdiagonal (if UPLO = 'L') are overwritten by the !> off-diagonal elements of T; the rest of AB is overwritten by !> values generated during the reduction. !>
LDAB
!> LDAB is INTEGER !> The leading dimension of the array AB. LDAB >= KD+1. !>
D
!> D is DOUBLE PRECISION array, dimension (N) !> The diagonal elements of the tridiagonal matrix T. !>
E
!> E is DOUBLE PRECISION array, dimension (N-1) !> The off-diagonal elements of the tridiagonal matrix T: !> E(i) = T(i,i+1) if UPLO = 'U'; E(i) = T(i+1,i) if UPLO = 'L'. !>
Q
!> Q is COMPLEX*16 array, dimension (LDQ,N) !> On entry, if VECT = 'U', then Q must contain an N-by-N !> matrix X; if VECT = 'N' or 'V', then Q need not be set. !> !> On exit: !> if VECT = 'V', Q contains the N-by-N unitary matrix Q; !> if VECT = 'U', Q contains the product X*Q; !> if VECT = 'N', the array Q is not referenced. !>
LDQ
!> LDQ is INTEGER !> The leading dimension of the array Q. !> LDQ >= 1, and LDQ >= N if VECT = 'V' or 'U'. !>
WORK
!> WORK is COMPLEX*16 array, dimension (N) !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Further Details:
!> !> Modified by Linda Kaufman, Bell Labs. !>
Definition at line 161 of file zhbtrd.f.
Author¶
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Version 3.12.0 | LAPACK |