.TH "SRC/zhbtrd.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/zhbtrd.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBzhbtrd\fP (vect, uplo, n, kd, ab, ldab, d, e, q, ldq, work, info)"
.br
.RI "\fBZHBTRD\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "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)"

.PP
\fBZHBTRD\fP  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
!>
!> ZHBTRD reduces a complex Hermitian band matrix A to real symmetric
!> tridiagonal form T by a unitary similarity transformation:
!> Q**H * A * Q = T\&.
!> 
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fIVECT\fP 
.PP
.nf
!>          VECT is CHARACTER*1
!>          = 'N':  do not form Q;
!>          = 'V':  form Q;
!>          = 'U':  update a matrix X, by forming X*Q\&.
!> 
.fi
.PP
.br
\fIUPLO\fP 
.PP
.nf
!>          UPLO is CHARACTER*1
!>          = 'U':  Upper triangle of A is stored;
!>          = 'L':  Lower triangle of A is stored\&.
!> 
.fi
.PP
.br
\fIN\fP 
.PP
.nf
!>          N is INTEGER
!>          The order of the matrix A\&.  N >= 0\&.
!> 
.fi
.PP
.br
\fIKD\fP 
.PP
.nf
!>          KD is INTEGER
!>          The number of superdiagonals of the matrix A if UPLO = 'U',
!>          or the number of subdiagonals if UPLO = 'L'\&.  KD >= 0\&.
!> 
.fi
.PP
.br
\fIAB\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fILDAB\fP 
.PP
.nf
!>          LDAB is INTEGER
!>          The leading dimension of the array AB\&.  LDAB >= KD+1\&.
!> 
.fi
.PP
.br
\fID\fP 
.PP
.nf
!>          D is DOUBLE PRECISION array, dimension (N)
!>          The diagonal elements of the tridiagonal matrix T\&.
!> 
.fi
.PP
.br
\fIE\fP 
.PP
.nf
!>          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'\&.
!> 
.fi
.PP
.br
\fIQ\fP 
.PP
.nf
!>          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\&.
!> 
.fi
.PP
.br
\fILDQ\fP 
.PP
.nf
!>          LDQ is INTEGER
!>          The leading dimension of the array Q\&.
!>          LDQ >= 1, and LDQ >= N if VECT = 'V' or 'U'\&.
!> 
.fi
.PP
.br
\fIWORK\fP 
.PP
.nf
!>          WORK is COMPLEX*16 array, dimension (N)
!> 
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!> 
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 

.PP
Univ\&. of California Berkeley 

.PP
Univ\&. of Colorado Denver 

.PP
NAG Ltd\&. 
.RE
.PP
\fBFurther Details:\fP
.RS 4

.PP
.nf
!>
!>  Modified by Linda Kaufman, Bell Labs\&.
!> 
.fi
.PP
 
.RE
.PP

.PP
Definition at line \fB161\fP of file \fBzhbtrd\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.