topic C++ ?imatcopy in Intel® oneAPI Math Kernel Library

C++ ?imatcopy

Andrew_Drach — Mon, 24 May 2010 16:51:23 GMT

Hi everyone,

Does anybody know how to use mkl_?imatcopy? I cannot get it working on my system. I use a lot of other MKL routines without a glitch but this one does not do anything :(

I work in MSVC 2008 with MKL 10.2

C++ ?imatcopy

Gennady_F_Intel — Mon, 24 May 2010 17:53:01 GMT

Hi krfighter,

in's not clear what do you mean by "but this one does not do anything"?

is that mean the input array == the output one?

--Gennady

C++ ?imatcopy

Vladimir_Koldakov__I — Mon, 24 May 2010 17:53:58 GMT

Hello,
Could you please provide a testcase?
It's not cleare what are you trying to do.
Thanks,
Vladimir

C++ ?imatcopy

Andrew_Drach — Wed, 26 May 2010 02:11:03 GMT

I am terribly sorry that first post was not clear enough.

Yes, input equals to output for some reason.

Here is an example code:

using namespace boost::numeric::ublas;

double K(3.0);

matrix D1;

D1.resize(3,3);

for (int i=0;i<3;++i) for (int j=0;j<3;++j) D1(i,j)=1.0;

mkl_dimatcopy(CblasRowMajor,CblasNoTrans,3,3,K,&D1(0,0),3,3);

P.S. Is it just me or all MKL developers are Russian? :) !

C++ ?imatcopy

Vladimir_Petrov__Int — Wed, 26 May 2010 03:10:42 GMT

Hello,

My first guess is that you are passing CblasNoTrans to mkl_dimatcopy.

My second thought is that you may be simply scaling...
In this case I wonder what D1 and D2 are in your example?

Best regards,
Vladimir (yet another one)

C++ ?imatcopy

Andrew_Drach — Wed, 26 May 2010 03:55:18 GMT

Yes, I do not need transposition.

Yes, I thought I could use this procedure for simple scaling (scalar multiplication)

Sorry, it should be D1 in both cases. Already corrected

C++ ?imatcopy

Vladimir_Petrov__Int — Thu, 27 May 2010 07:35:54 GMT

Andrew,

The root cause of the problem is using Cblas constants instead of the chars ('R' for row-major, and 'N' for no action) as documented in the MKL manual.

Please use
mkl_dimatcopy('R','N',3,3,K,&(D1(0,0)),3,3);
instead of
mkl_dimatcopy(CblasRowMajor,CblasNoTrans,3,3,K,&D1(0,0),3,3);

Best regards,
Vladimir

C++ ?imatcopy

Andrew_Drach — Sat, 29 May 2010 10:12:34 GMT

Vladimir,

Thanks a lot!

Such a silly mistake to mess it up with CBLAS interface constants...