def _param_grad_helper(self,dL_dK,X,X2,target):
AX = np.dot(X,self.transform)<EOL>if X2 is None:<EOL><INDENT>X2 = X<EOL>ZX2 = AX<EOL><DEDENT>else:<EOL><INDENT>AX2 = np.dot(X2, self.transform)<EOL><DEDENT>self.k._param_grad_helper(dL_dK,X,X2,target)<EOL>self.k._param_grad_helper(dL_dK,AX,X2,target)<EOL>self.k._param_grad_helper(dL_dK,X,AX2,target)<EOL>self.k._param_grad_helper(dL_dK,AX,AX2,target)<EOL>
derivative of the covariance matrix with respect to the parameters.