get resolution Matrix (V_1 * V_1^T) at a singular value

        Parameters
        ----------
        singular_value : int
            singular value to calc R at

        Returns
        -------
        R : pyemu.Matrix
            resolution matrix at singular_value

def R(self, singular_value):
        """get resolution Matrix (V_1 * V_1^T) at a singular value

        Parameters
        ----------
        singular_value : int
            singular value to calc R at

        Returns
        -------
        R : pyemu.Matrix
            resolution matrix at singular_value
        """
        if self.__R is not None and singular_value == self.__R_sv:
            return self.__R

        elif singular_value > self.jco.ncol:
            self.__R_sv = self.jco.ncol
            return self.parcov.identity
        else:
            self.log("calc R @" + str(singular_value))
            #v1 = self.qhalfx.v[:, :singular_value]
            v1 = self.xtqx.v[:, :singular_value]
            self.__R = v1 * v1.T
            self.__R_sv = singular_value
            self.log("calc R @" + str(singular_value))
            return self.__R