void remove_avg_row(mat& m){
cout<<"remove row average..."<<endl;
for(mat::iterator1 i=m.begin1(); i!=m.end1(); ++i){
int count=0; double sum=0;
for(mat::iterator2 j=i.begin(); j!=i.end(); ++j){
count++; sum += *j;
}
if(count==0 || sum==0) continue;
double avg = sum / count;
for(mat::iterator2 j=i.begin(); j!=i.end(); ++j){
*j -= avg;
}
}
}
