comment improvement and a mistake on variable name fixed.
comment improvement and a mistake on variable name fixed.

keisuke-umezawa/chainer,ronekko/chainer,hvy/chainer,hvy/chainer,wkentaro/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,okuta/chainer,jnishi/chainer,rezoo/chainer,tkerola/chainer,jnishi/chainer,keisuke-umezawa/chainer,pfnet/chainer,wkentaro/chainer,niboshi/chainer,ktnyt/chainer,okuta/chainer,chainer/chainer,jnishi/chainer,ktnyt/chainer,chainer/chainer,ktnyt/chainer,hvy/chainer,chainer/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,okuta/chainer,ktnyt/chainer,chainer/chainer,niboshi/chainer,wkentaro/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer