sgbbrd(3P) Sun Performance Library sgbbrd(3P)NAMEsgbbrd - reduce a real general m-by-n band matrix A to upper bidiagonal
form B by an orthogonal transformation
SYNOPSIS
SUBROUTINE SGBBRD(VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q, LDQ,
PT, LDPT, C, LDC, WORK, INFO)
CHARACTER * 1 VECT
INTEGER M, N, NCC, KL, KU, LDAB, LDQ, LDPT, LDC, INFO
REAL AB(LDAB,*), D(*), E(*), Q(LDQ,*), PT(LDPT,*), C(LDC,*), WORK(*)
SUBROUTINE SGBBRD_64(VECT, M, N, NCC, KL, KU, AB, LDAB, D, E, Q, LDQ,
PT, LDPT, C, LDC, WORK, INFO)
CHARACTER * 1 VECT
INTEGER*8 M, N, NCC, KL, KU, LDAB, LDQ, LDPT, LDC, INFO
REAL AB(LDAB,*), D(*), E(*), Q(LDQ,*), PT(LDPT,*), C(LDC,*), WORK(*)
F95 INTERFACE
SUBROUTINE GBBRD(VECT, M, [N], [NCC], KL, KU, AB, [LDAB], D, E, Q,
[LDQ], PT, [LDPT], C, [LDC], [WORK], [INFO])
CHARACTER(LEN=1) :: VECT
INTEGER :: M, N, NCC, KL, KU, LDAB, LDQ, LDPT, LDC, INFO
REAL, DIMENSION(:) :: D, E, WORK
REAL, DIMENSION(:,:) :: AB, Q, PT, C
SUBROUTINE GBBRD_64(VECT, M, [N], [NCC], KL, KU, AB, [LDAB], D, E,
Q, [LDQ], PT, [LDPT], C, [LDC], [WORK], [INFO])
CHARACTER(LEN=1) :: VECT
INTEGER(8) :: M, N, NCC, KL, KU, LDAB, LDQ, LDPT, LDC, INFO
REAL, DIMENSION(:) :: D, E, WORK
REAL, DIMENSION(:,:) :: AB, Q, PT, C
C INTERFACE
#include <sunperf.h>
void sgbbrd(char vect, int m, int n, int ncc, int kl, int ku, float
*ab, int ldab, float *d, float *e, float *q, int ldq, float
*pt, int ldpt, float *c, int ldc, int *info);
void sgbbrd_64(char vect, long m, long n, long ncc, long kl, long ku,
float *ab, long ldab, float *d, float *e, float *q, long ldq,
float *pt, long ldpt, float *c, long ldc, long *info);
PURPOSEsgbbrd reduces a real general m-by-n band matrix A to upper bidiagonal
form B by an orthogonal transformation: Q' * A * P = B.
The routine computes B, and optionally forms Q or P', or computes Q'*C
for a given matrix C.
ARGUMENTS
VECT (input)
Specifies whether or not the matrices Q and P' are to be
formed. = 'N': do not form Q or P';
= 'Q': form Q only;
= 'P': form P' only;
= 'B': form both.
M (input) The number of rows of the matrix A. M >= 0.
N (input) The number of columns of the matrix A. N >= 0.
NCC (input)
The number of columns of the matrix C. NCC >= 0.
KL (input)
The number of subdiagonals of the matrix A. KL >= 0.
KU (input)
The number of superdiagonals of the matrix A. KU >= 0.
AB (input/output)
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 reduc‐
tion.
LDAB (input)
The leading dimension of the array A. LDAB >= KL+KU+1.
D (output)
REAL array, dimension(min(M,N)) The diagonal elements of the
bidiagonal matrix B.
E (output)
REAL array, dimension(min(M,N)-1) The superdiagonal elements
of the bidiagonal matrix B.
Q (output)
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 (input)
The leading dimension of the array Q. LDQ >= max(1,M) if
VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
PT (output)
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 (input)
The leading dimension of the array PT. LDPT >= max(1,N) if
VECT = 'P' or 'B'; LDPT >= 1 otherwise.
C (input/output)
REAL array, dimension(LDC.NCC) On entry, an m-by-ncc matrix
C. On exit, C is overwritten by Q'*C. C is not referenced
if NCC = 0.
LDC (input)
The leading dimension of the array C. LDC >= max(1,M) if NCC
> 0; LDC >= 1 if NCC = 0.
WORK (workspace)
REAL array, dimension(2*MAX(M,N))
INFO (output)
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value.
6 Mar 2009 sgbbrd(3P)
