#NEWLINE# def backward_gpu( self , x , gy ) : #NEWLINE# #INDENT# gx = cuda . elementwise ( 'T x, T gy, T alpha' , 'T gx' , 'gx = x >= 0 ? gy : gy * alpha * exp(x)' , 'elu_bwd' ) ( x [ 0 ] , gx [ 0 ] , self . alpha ) #NEWLINE# return ( gx , )