Minor/trivial speedup: preallocate the matrix.
Minor/trivial speedup: preallocate the matrix.

erubboli/mlpack,erubboli/mlpack,ajjl/mlpack,thirdwing/mlpack,minhpqn/mlpack,chenmoshushi/mlpack,thirdwing/mlpack,stereomatchingkiss/mlpack,Azizou/mlpack,ranjan1990/mlpack,theranger/mlpack,stereomatchingkiss/mlpack,datachand/mlpack,ersanliqiao/mlpack,trungda/mlpack,trungda/mlpack,thirdwing/mlpack,erubboli/mlpack,lezorich/mlpack,stereomatchingkiss/mlpack,palashahuja/mlpack,minhpqn/mlpack,minhpqn/mlpack,Azizou/mlpack,darcyliu/mlpack,bmswgnp/mlpack,palashahuja/mlpack,BookChan/mlpack,ranjan1990/mlpack,theranger/mlpack,ajjl/mlpack,BookChan/mlpack,ranjan1990/mlpack,darcyliu/mlpack,ajjl/mlpack,lezorich/mlpack,palashahuja/mlpack,Azizou/mlpack,ersanliqiao/mlpack,datachand/mlpack,bmswgnp/mlpack,darcyliu/mlpack,BookChan/mlpack,bmswgnp/mlpack,lezorich/mlpack,chenmoshushi/mlpack,theranger/mlpack,trungda/mlpack,ersanliqiao/mlpack,datachand/mlpack,chenmoshushi/mlpack