topic What do you mean by "However, in Intel® oneAPI Math Kernel Library

Problem of cblas_zgemmt

Li__Xinyi — Wed, 07 Feb 2018 15:06:34 GMT

I would like to use cblas_zgemmt() to calculate C=C-A*B. The final C is symmetrical.

The input matrices is verified by cblas_zgemm() and the result is correct. However, the output C is unchanged when cblas_zgemmt() is used.

Should the input matrices of zgemmt() be different from zgemm()?

Thanks a lot!

Kimi Lee

What do you mean by "However,

mecej4 — Wed, 07 Feb 2018 22:36:16 GMT

What do you mean by "However, the output C is unchanged when cblas_zgemmt() is used" ? That the output C is the same as that which cblas_zgemm() gave? Or that the output C is the same as the input C?

It is up to you to know in advance that the result C is symmetric. If that is true, the cblas_zgemmt() routine will give the same result as cblas_zgemm(), but will update only the upper or lower triangle of C, as specified by you. Thus, cblas_zgemmt() will be nearly twice as fast as cblas_zgemm().

Thanks for the answer.

Li__Xinyi — Thu, 08 Feb 2018 03:22:49 GMT

Thanks for the answer.

I fixed this problem. The developer reference of cblas_?gemmt has some problems. uplo should be CblasUpper instead of 'U'. Moreover, the explaination of lda and ldb is incorrect in the case of CblasColMajor.

By the way, are there any

Li__Xinyi — Thu, 08 Feb 2018 04:18:29 GMT

By the way, are there any routines could mirror the upper triangular matrix to lower triangular matrix after using gemmt()?

thanks for these tips, we

Gennady_F_Intel — Thu, 08 Feb 2018 04:46:01 GMT

thanks for these tips, we definitely will correct these.