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Li__Xinyi

Beginner

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02-07-2018
07:06 AM

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Problem of cblas_zgemmt

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

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4 Replies

mecej4

Black Belt

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02-07-2018
02:36 PM

22 Views

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().

Li__Xinyi

Beginner

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02-07-2018
07:22 PM

22 Views

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.

Li__Xinyi

Beginner

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02-07-2018
08:18 PM

22 Views

Gennady_F_Intel

Moderator

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02-07-2018
08:46 PM

22 Views

thanks for these tips, we definitely will correct these.

For more complete information about compiler optimizations, see our Optimization Notice.