求助：DGBTRS - 未名空间MITBBS历史存档

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求助：DGBTRS

求助：DGBTRS# Computation - 科学计算

w*t2007-06-14 07:06

1 楼

我要解一个线性方程组，矩阵是条形的，想用Lapack里的DGBTRS solver，如下
DGBTRS( TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO )
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.
LDAB (input) INTEGER
* The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
LDAB 这个不懂，大家可以解释一下怎样确定一个matrix的 LDAB 吗？比如我要解
1 1 1 0
1 1 1 0
0 1 1 0
0 0 0 1
KL=1, KU=2, 对吗，LDAB是多少？
另外，听说

s*t2007-06-14 07:06

2 楼

the leading dimension is often used in LAPACK. it's basically
related to how you allocte your memory. and it follows the fortran
rule, i.e., column-order.
say you have a 5x5 matrix. but you can allocate a 10x10 block and
put the 5x5 matrix anywhere within the 10x10 block that fits. you
then tell the LAPACK routine the pointer to the first element of
the 5x5 matrix, and the leading dimension, which is 10, and the matrix
size, which is 5x5. then the routine will know where to find the
5x5 ma

【在 w**t 的大作中提到】

: 我要解一个线性方程组，矩阵是条形的，想用Lapack里的DGBTRS solver，如下
: DGBTRS( TRANS, N, KL, KU, NRHS, AB, LDAB, IPIV, B, LDB, INFO )
: 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.
: LDAB (input) INTEGER
: * The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
: LDAB 这个不懂，大家可以解释一下怎样确定一个matrix的 LDAB 吗？比如我要解
: 1 1 1 0