CGBBRD (3)  Linux Manuals
NAME
cgbbrd.f 
SYNOPSIS
Functions/Subroutines
subroutine cgbbrd (VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q, LDQ, PT, LDPT, C, LDC, WORK, RWORK, INFO)
CGBBRD
Function/Subroutine Documentation
subroutine cgbbrd (characterVECT, integerM, integerN, integerNCC, integerKL, integerKU, complex, dimension( ldab, * )AB, integerLDAB, real, dimension( * )D, real, dimension( * )E, complex, dimension( ldq, * )Q, integerLDQ, complex, dimension( ldpt, * )PT, integerLDPT, complex, dimension( ldc, * )C, integerLDC, complex, dimension( * )WORK, real, dimension( * )RWORK, integerINFO)
CGBBRD
Purpose:

CGBBRD reduces a complex general mbyn band matrix A to real upper bidiagonal form B by a unitary transformation: Q**H * A * P = B. The routine computes B, and optionally forms Q or P**H, or computes Q**H*C for a given matrix C.
Parameters:

VECT
VECT is CHARACTER*1 Specifies whether or not the matrices Q and P**H are to be formed. = 'N': do not form Q or P**H; = 'Q': form Q only; = 'P': form P**H only; = 'B': form both.
MM is INTEGER The number of rows of the matrix A. M >= 0.
NN is INTEGER The number of columns of the matrix A. N >= 0.
NCCNCC is INTEGER The number of columns of the matrix C. NCC >= 0.
KLKL is INTEGER The number of subdiagonals of the matrix A. KL >= 0.
KUKU is INTEGER The number of superdiagonals of the matrix A. KU >= 0.
ABAB is COMPLEX array, dimension (LDAB,N) On entry, the mbyn band matrix A, stored in rows 1 to KL+KU+1. The jth column of A is stored in the jth column of the array AB as follows: AB(ku+1+ij,j) = A(i,j) for max(1,jku)<=i<=min(m,j+kl). On exit, A is overwritten by values generated during the reduction.
LDABLDAB is INTEGER The leading dimension of the array A. LDAB >= KL+KU+1.
DD is REAL array, dimension (min(M,N)) The diagonal elements of the bidiagonal matrix B.
EE is REAL array, dimension (min(M,N)1) The superdiagonal elements of the bidiagonal matrix B.
QQ is COMPLEX array, dimension (LDQ,M) If VECT = 'Q' or 'B', the mbym unitary matrix Q. If VECT = 'N' or 'P', the array Q is not referenced.
LDQLDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
PTPT is COMPLEX array, dimension (LDPT,N) If VECT = 'P' or 'B', the nbyn unitary matrix P'. If VECT = 'N' or 'Q', the array PT is not referenced.
LDPTLDPT is INTEGER The leading dimension of the array PT. LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise.
CC is COMPLEX array, dimension (LDC,NCC) On entry, an mbyncc matrix C. On exit, C is overwritten by Q**H*C. C is not referenced if NCC = 0.
LDCLDC is INTEGER The leading dimension of the array C. LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0.
WORKWORK is COMPLEX array, dimension (max(M,N))
RWORKRWORK is REAL array, dimension (max(M,N))
INFOINFO is INTEGER = 0: successful exit. < 0: if INFO = i, the ith argument had an illegal value.
Author:

Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
 November 2011
Definition at line 193 of file cgbbrd.f.
Author
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