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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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LAPACK 3.11.0
LAPACK: Linear Algebra PACKage
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| 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
Download SGBBRD + dependencies [TGZ] [ZIP] [TXT]
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.
| [in] | 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. |
| [in] | M | M is INTEGER
The number of rows of the matrix A. M >= 0. |
| [in] | N | N is INTEGER
The number of columns of the matrix A. N >= 0. |
| [in] | NCC | NCC is INTEGER
The number of columns of the matrix C. NCC >= 0. |
| [in] | KL | KL is INTEGER
The number of subdiagonals of the matrix A. KL >= 0. |
| [in] | KU | KU is INTEGER
The number of superdiagonals of the matrix A. KU >= 0. |
| [in,out] | 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. |
| [in] | LDAB | LDAB is INTEGER
The leading dimension of the array A. LDAB >= KL+KU+1. |
| [out] | D | D is REAL array, dimension (min(M,N))
The diagonal elements of the bidiagonal matrix B. |
| [out] | E | E is REAL array, dimension (min(M,N)-1)
The superdiagonal elements of the bidiagonal matrix B. |
| [out] | 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. |
| [in] | LDQ | LDQ is INTEGER
The leading dimension of the array Q.
LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise. |
| [out] | 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. |
| [in] | LDPT | LDPT is INTEGER
The leading dimension of the array PT.
LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise. |
| [in,out] | 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. |
| [in] | LDC | LDC is INTEGER
The leading dimension of the array C.
LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0. |
| [out] | WORK | WORK is REAL array, dimension (2*max(M,N)) |
| [out] | INFO | INFO is INTEGER
= 0: successful exit.
< 0: if INFO = -i, the i-th argument had an illegal value. |
1.9.4