I am using the library of boost to create a 2D dimensions array

and compare about their speed

There are three kinds of array, matrix of boost, multi_array of boost and the raw array

Below is my code:

```
#ifndef TESTRELMAT_H
#define TESTRELMAT_H
#define BOOST_NO_EXCEPTIONS
#define BOOST_DISABLE_ASSERTS
#include <boost/numeric/ublas/matrix.hpp>
#include <boost/multi_array.hpp>
using boost::multi_array;
using boost::numeric::ublas::matrix;
#define _SECURE_SCL 0
#include<vector>
#include<algorithm>
#include<ctime>
void testRelMat()
{
const int row = 1000;
const int column = 1000;
std::vector<unsigned char> sorted( 9 );
std::clock_t begin, end;
matrix<unsigned char> data(row, column);
typedef boost::numeric::ublas::zero_matrix<unsigned char> zMat;
matrix<unsigned char> temp( data.size1() + 2, data.size2() + 2);
int k = 0;
begin = std::clock();
for(unsigned int i = 0; i < data.size1(); i++)
for(unsigned int j = 0; j < data.size2(); j++)
{
for( unsigned int l = 0; l< 3; l++)
for( unsigned int m = 0; m < 3; m++)
{
sorted[k] = temp(i + l, j + m);
k++;
}
k = 0;
std::sort(sorted.begin(), sorted.end());
data.insert_element( i, j, sorted[4] );
}
end = std::clock();
cout<<"time of ublas : "<<(double)(end-begin)/CLOCKS_PER_SEC<<" "<<endl;
multi_array<unsigned char, 2> dataArr(boost::extents[row][column]);
multi_array<unsigned char, 2> tempArr(boost::extents[row + 2][column + 2]);
int medium = 0;
begin = std::clock();
for(unsigned int i = 0; i < data.size1(); i++)
for(unsigned int j = 0; j < data.size2(); j++)
{
for( unsigned int l = 0; l< 3; l++)
for( unsigned int m = 0; m < 3; m++)
{
sorted[medium] = tempArr[i + l][j + m];
medium++;
}
medium = 0;
std::sort(sorted.begin(), sorted.end());
dataArr[i][j] = sorted[4];
}
end = std::clock();
cout<<"time of multi array : "<<(double)(end-begin)/CLOCKS_PER_SEC<<" "<<endl;
unsigned char **pp;
pp = new unsigned char* [column];
for(unsigned int i = 0; i < column; i++)
*(pp + i)=new unsigned char[row];
unsigned char **temp2 = new unsigned char *[row + 2];
for(unsigned int i = 0; i < row + 2; ++i)
*(temp2 + i) = new unsigned char[column + 2];
int med = 0;
begin = std::clock();
for(unsigned int i = 0; i < column; i++)
for(unsigned int j = 0; j < row; j++)
{
for( unsigned int l = 0; l< 3; l++)
for( unsigned int m = 0; m < 3; m++)
{
sorted[med] = temp2[i + l][j + m];
med++;
}
med = 0;
std::sort(sorted.begin(), sorted.end());
pp[i][j] = sorted[4];
}
end = std::clock();
cout<<"time of raw array : "<<(double)(end-begin)/CLOCKS_PER_SEC<<" "<<endl;
for(unsigned int i = 0; i < column; ++i)
delete [] pp[i];
delete [] pp;
for(unsigned int i = 0; i < 290; ++i)
delete [] temp2[i];
delete [] temp2;
/*unsigned char** pp = unsigned char* [column];
pp[0] = unsigned char [column * row];
for (unsigned int i = 1; i < column; ++i)
pp[i] = pp[i-1] + row;
delete [] pp[0];
delete [] pp;*/
}
#endif
```

My compiler is visualC++ 2008 express edition, my OS is windows xp sp3. Below is the results of the release version.

```
time of ublas : 0.156
time of multi_array : 0.172
time of raw array : 0.094
Obviously, the raw array is faster than the dynamic array of ublas and multi_array. Do I made any mistakes? Are there any ways
could improve the speed?Thanks
```