Re: [ublas] numeric bindings nrm2 differences

Subject: Re: [ublas] numeric bindings nrm2 differences
From: Kraus Philipp (philipp.kraus_at_[hidden])
Date: 2011-11-29 14:35:17

Am 29.11.2011 um 19:25 schrieb Thomas Klimpel:

> Kraus Philipp wrote:
>> The C++ Code ist build with 
>> g++ text.cpp -I/Developer/opt/Boost/1.48.0/include -I/Developer/opt/Boost/sandbox/numeric_bindings -latlas -lf77blas -lcblas
>> 
>> Matlab result: 1.897052466920491
>> C++ result: blas:	1.46849
>> 	    ublas:	1.46849
> 
> I tried to reproduce (I even installed boost-1.48), but I got
> ublas:  1.89705

mmmh, that's bad. I'm using boost 1.48 also. Should I downgrade my Boost version (I have installed the 1.47)?

> 
> Can you remove the call to "blas::nrm2(vec3)" or at least call "ublas::norm_2(vec3)" first, so that "memory corruption" by "blas::nrm2(vec3)" can be excluded?
> 
> 
>> If I compile it with -D BOOST_NUMERIC_BINDINGS_BLAS_CBLAS flag, I get errors eg:
> 
> You need to add the include path for atlas to the compile line...
> 

Yes, I've forgot ist. But with the CBLAS flag the result ist also 1.46849

> 
>> The parameter n is the vector.size(), x the vector, isn't it?
> 
> Correct.
> 
>> Which definition has incx?
> 
> You should set it to "1" for this case.
> 

I have add the line std::cout << "cblas:\t" << cblas_dnrm2( vec3.size(), &vec3(0), 1 ) << std::endl; 
to my example. All values are 1.46849 again.

I have updated the bindings to 75728

I am a little perplexed

Phil