table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgbbrd.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgbbrd.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/sgbbrd.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine SGBBRD (vect, m, n, ncc, kl, ku, ab, ldab, d, e,
q, ldq, pt, ldpt, c, ldc, work, info)
SGBBRD
Function/Subroutine Documentation¶
subroutine SGBBRD (character vect, integer m, integer n, integer ncc, integer kl, integer ku, real, dimension( ldab, * ) ab, integer ldab, real, dimension( * ) d, real, dimension( * ) e, real, dimension( ldq, * ) q, integer ldq, real, dimension( ldpt, * ) pt, integer ldpt, real, dimension( ldc, * ) c, integer ldc, real, dimension( * ) work, integer info)¶
SGBBRD
Purpose:
!> !> SGBBRD reduces a real general m-by-n band matrix A to upper !> bidiagonal form B by an orthogonal transformation: Q**T * A * P = B. !> !> The routine computes B, and optionally forms Q or P**T, or computes !> Q**T*C for a given matrix C. !>
Parameters
VECT
!> VECT is CHARACTER*1 !> Specifies whether or not the matrices Q and P**T are to be !> formed. !> = 'N': do not form Q or P**T; !> = 'Q': form Q only; !> = 'P': form P**T only; !> = 'B': form both. !>
M
!> M is INTEGER !> The number of rows of the matrix A. M >= 0. !>
N
!> N is INTEGER !> The number of columns of the matrix A. N >= 0. !>
NCC
!> NCC is INTEGER !> The number of columns of the matrix C. NCC >= 0. !>
KL
!> KL is INTEGER !> The number of subdiagonals of the matrix A. KL >= 0. !>
KU
!> KU is INTEGER !> The number of superdiagonals of the matrix A. KU >= 0. !>
AB
!> AB is REAL 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. !>
LDAB
!> LDAB is INTEGER !> The leading dimension of the array A. LDAB >= KL+KU+1. !>
D
!> D is REAL array, dimension (min(M,N)) !> The diagonal elements of the bidiagonal matrix B. !>
E
!> E is REAL array, dimension (min(M,N)-1) !> The superdiagonal elements of the bidiagonal matrix B. !>
Q
!> Q is REAL array, dimension (LDQ,M) !> If VECT = 'Q' or 'B', the m-by-m orthogonal matrix Q. !> If VECT = 'N' or 'P', the array Q is not referenced. !>
LDQ
!> LDQ is INTEGER !> The leading dimension of the array Q. !> LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise. !>
PT
!> PT is REAL array, dimension (LDPT,N) !> If VECT = 'P' or 'B', the n-by-n orthogonal matrix P'. !> If VECT = 'N' or 'Q', the array PT is not referenced. !>
LDPT
!> LDPT is INTEGER !> The leading dimension of the array PT. !> LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise. !>
C
!> C is REAL array, dimension (LDC,NCC) !> On entry, an m-by-ncc matrix C. !> On exit, C is overwritten by Q**T*C. !> C is not referenced if NCC = 0. !>
LDC
!> LDC is INTEGER !> The leading dimension of the array C. !> LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0. !>
WORK
!> WORK is REAL array, dimension (2*max(M,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.
Definition at line 185 of file sgbbrd.f.
Author¶
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