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lda in lapack and cublas

萨科潘 2022-03-11 阅读 59
p2plinqgnu

在BLAS-3.10.01 的 sgemm.f 文件中,有如下对LDA的描述:

\param[in] A
*> \verbatim
*>          A is REAL array, dimension ( LDA, ka ), where ka is
*>           k  when  TRANSA = 'N' or 'n',  and is  m  otherwise.
*>           Before entry with  TRANSA = 'N' or 'n',  the leading  m by k
*>           part of the array  A  must contain the matrix  A,  otherwise
*>           the leading  k by m  part of the array  A  must contain  the
*>           matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>           On entry, LDA specifies the first dimension of A as declared
*>           in the calling (sub) program. When  TRANSA = 'N' or 'n' then
*>           LDA must be at least  max( 1, m ), otherwise  LDA must be at
*>           least  max( 1, k ).
*> \endverbatim

LDA 是矩阵中一列数据的长度,要么LDA>=m, 要么LDA>=k;

当 TRANSA = 'N' 时, LDA>=m; 这时,输入指针A指向的数据区域,是将一个矩阵Matrix_A(LDA, K) 按照列主序一维化存储下来的结果。

当TRANSA = 'T' 时, LDA>=k; 这时,输入指针A指向的数据区域,是将一个矩阵Matrix_A(LDA, M) 按照列主序一维化存储下来的结果,这时矩阵Matrix_A是以矩阵A的转置方式输入给函数SGEMM的。

ldb的理解,和 B 所给出的数据也一样。

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