get the null space term (first term) contribution to parameter error variance
            at a singular value

        Parameters
        ----------
        singular_value : int
            singular value to calc first term at

        Returns
        -------
        first_term : pyemu.Cov
            first term contribution to parameter error variance

def first_parameter(self, singular_value):
        """get the null space term (first term) contribution to parameter error variance
            at a singular value

        Parameters
        ----------
        singular_value : int
            singular value to calc first term at

        Returns
        -------
        first_term : pyemu.Cov
            first term contribution to parameter error variance

        """
        self.log("calc first term parameter @" + str(singular_value))
        first_term = self.I_minus_R(singular_value) * self.parcov * \
                     self.I_minus_R(singular_value)
        self.log("calc first term parameter @" + str(singular_value))
        return first_term