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NAME¶
SDBTF2 - compute an LU factorization of a real m-by-n band matrix A without using partial pivoting with row interchangesSYNOPSIS¶
- SUBROUTINE SDBTF2(
- M, N, KL, KU, AB, LDAB, INFO )
- INTEGER
- INFO, KL, KU, LDAB, M, N
- REAL
- AB( LDAB, * )
PURPOSE¶
Sdbtrf computes an LU factorization of a real m-by-n band matrix A without using partial pivoting with row interchanges.ARGUMENTS¶
- M (input) INTEGER
- The number of rows of the matrix A. M >= 0.
- N (input) INTEGER
- The number of columns of the matrix A. N >= 0.
- KL (input) INTEGER
- The number of subdiagonals within the band of A. KL >= 0.
- KU (input) INTEGER
- The number of superdiagonals within the band of A. KU >= 0.
- AB (input/output) REAL array, dimension (LDAB,N)
- On entry, the matrix A in band storage, in rows KL+1 to
2*KL+KU+1; rows 1 to KL of the array need not be set. The j-th column of A
is stored in the j-th column of the array AB as follows: AB(kl+ku+1+i-j,j)
= A(i,j) for max(1,j-ku)<=i<=min(m,j+kl)
- LDAB (input) INTEGER
- The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
- INFO (output) INTEGER
- = 0: successful exit
FURTHER DETAILS¶
The band storage scheme is illustrated by the following example, when M = N = 6, KL = 2, KU = 1:* a12 a23 a34 a45 a56 * u12 u23 u34 u45 u56
a11 a22 a33 a44 a55 a66 u11 u22 u33 u44 u55 u66
a21 a32 a43 a54 a65 * m21 m32 m43 m54 m65 *
a31 a42 a53 a64 * * m31 m42 m53 m64 * *
June 7, 2017 |