Add TODO comment to improve performance of reciprocal
Add TODO comment to improve performance of reciprocal

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