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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. |