cgbbrd.f (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 m-by-n 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 m-by-n band matrix A, stored in rows 1 to KL+KU+1. The j-th column of A is stored in the j-th column of the array AB as follows: AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=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 m-by-m 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 n-by-n 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 m-by-ncc 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 i-th 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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