Implement argmax and argmin
Implement argmax and argmin

okuta/chainer,hvy/chainer,cupy/cupy,hvy/chainer,keisuke-umezawa/chainer,niboshi/chainer,kikusu/chainer,cupy/cupy,okuta/chainer,ktnyt/chainer,chainer/chainer,kiyukuta/chainer,niboshi/chainer,hvy/chainer,chainer/chainer,jnishi/chainer,ktnyt/chainer,jnishi/chainer,ronekko/chainer,pfnet/chainer,anaruse/chainer,aonotas/chainer,keisuke-umezawa/chainer,cupy/cupy,wkentaro/chainer,delta2323/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,wkentaro/chainer,kikusu/chainer,jnishi/chainer,hvy/chainer,ktnyt/chainer,keisuke-umezawa/chainer,cupy/cupy,keisuke-umezawa/chainer,niboshi/chainer,ktnyt/chainer,chainer/chainer,wkentaro/chainer,niboshi/chainer,tkerola/chainer,jnishi/chainer,okuta/chainer,kashif/chainer,rezoo/chainer,ysekky/chainer