Re: [ublas] question about a binding of ublas

Subject: Re: [ublas] question about a binding of ublas
From: Kaveh Kohan (kaveh.kohan_at_[hidden])
Date: 2010-11-02 14:54:20

Hi Rutger,

Thank you very much for your reply.

I think the version of boost I am using is quite old (1.35.0) and it seems that 
there have been significant changes with respect to the current version (is it 
1.6?).  For example I came to realize and you also pointed out that atlas is not 
a binding anymore and it seems that its functionalities are provided via BLAS 
and LAPACK bindings as you said. Now my question is that do we need to link with 
libatlas.so to use the functionalities or libcblas.so in enough (in case one 
wants to use ATLAS).

Here is my specific question:
Please correct me if I am wrong but it seems that there is a significant 
performance difference between, for example, matrix-matrix multiplication if one 
uses ublas comparing to atlas. Here is an example I am using to compare them:

kaevh_at_kavehpc:~/code/test_folder/cpp_test/boost_test1$ g++ test1.cpp -o test1 
-Wall -O3 -DNDEBUG -lcblas
kaevh_at_kavehpc:~/code/test_folder/cpp_test/boost_test1$ ./test1 1000 1000 1000
ublas  default implementation in blas
Time : 1.77262
default implementation in atlas
Time : 0.519718

------------------------------------------------ CODE
#include <iostream>
//#include <valarray>

#include <boost/numeric/ublas/matrix.hpp>
#include <boost/numeric/ublas/io.hpp>
#include <boost/timer.hpp>

#include <boost/numeric/bindings/atlas/cblas3.hpp>
#include <boost/numeric/bindings/traits/ublas_matrix.hpp>
namespace atlas = boost::numeric::bindings::atlas; 

# include <sys/time.h>

namespace ublas = boost::numeric::ublas;
using namespace std; 

double gettime() {
struct timeval t;
gettimeofday(&t, NULL);
return (double)t.tv_sec+t.tv_usec*0.000001;
}

void initmatrix(ublas::matrix<double>& A) {
 for(size_t i = 0; i<A.size1(); i++)
  for(size_t j = 0; j<A.size2(); j++)
   A(i,j) = 1.0*rand();
}
void initmatrix(ublas::matrix<double,ublas::column_major>& A) {
 for(size_t i = 0; i<A.size1(); i++)
  for(size_t j = 0; j<A.size2(); j++)
   A(i,j) = 1.0*rand();
} 

int main(int argc, char *argv[])
{
long int D,r,n ;

//std::clock_t start;
//double diff;
double t1,t2 ;

//D = 1000 ;
D = atoi(argv[1]) ;
//r = 1000 ;
r = atoi(argv[2]) ;
//n = 1000 ;
n = atoi(argv[3]) ;

   {
   cout << "ublas  ";

   ublas::matrix<double> A(D,r);
   ublas::matrix<double,ublas::column_major> B(r,n);
   ublas::matrix<double> X(D,n);
   initmatrix(A);
   initmatrix(B);

   cout << "default implementation in blas" << endl ;
   t1 = gettime() ;
   //X = ublas::prod< ublas::matrix<double> >(A,B);
   noalias(X) = ublas::prod(A,B) ;
   t2 = gettime() ;
   cout << "Time : " <<  t2 - t1 << endl; 

   
   }

   {
    ublas::matrix<double, ublas::column_major> A(D,r),B(r,n),C(D,n); 
    initmatrix(A);
    initmatrix(B);
   
   cout << "default implementation in atlas" << endl ;
   t1 = gettime() ;
   atlas::gemm(A,B,C); 
   t2 = gettime() ;
   cout << "Time : " <<  t2 - t1 << endl; 
   }  

}

________________________________
From: Rutger ter Borg <rutger_at_[hidden]>
To: ublas_at_[hidden]
Sent: Tue, November 2, 2010 3:42:37 AM
Subject: Re: [ublas] question about a binding of ublas

On 2010-11-02 04:12, Kaveh Kohan wrote:
> Hi Everyone,
>
> I would be thankful if anyone direct me to any documentation about
> bindings of ublas, more specifically I would like to know available
> functionalities available in atlas binding of the ublas. Unfortunately,
> I was unable to find them by googeling!
>
> Thanks,
> Kaveh
>

erm... I'll try that again.

Documentation is progressing slowly, and is at
http://svn.boost.org/svn/boost/sandbox/numeric_bindings/libs/numeric/bindings/doc/html/index.html

The bindings themselves may be checked out with subversion at

http://svn.boost.org/svn/boost/sandbox/numeric_bindings

ATLAS is supported through the BLAS bindings interface, enable them by 
defining BOOST_NUMERIC_BINDINGS_BLAS_CBLAS

ATLAS' lapack functionality is supported, too, through the LAPACK 
interface, enable them by defining BOOST_NUMERIC_BINDINGS_LAPACK_CLAPACK

HtH,
Cheers,

Rutger

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