def gradient(self):
        """The gradient operator."""
        return (ScalingOperator(self.domain, 1 / self.sigma) -
                (1 / self.sigma) * self.functional.proximal(self.sigma))
def gradient ( self ) : return ( ScalingOperator ( self . domain , 1 / self . sigma ) - ( 1 / self . sigma ) * self . functional . proximal ( self . sigma ) )
The gradient operator.