fix bug in single function of buck/long/coul/long

      f = s*(1.0-factor_coul)/r; s *= g_ewald*exp(-x*x);

      force_coul = (t *= ((((t*A5+A4)*t+A3)*t+A2)*t+A1)*s/x)+EWALD_F*s-f;

      eng += t-f;

    }

    else {                                                // table real space

    } else {                                                // table real space

      union_int_float_t t;

      t.f = rsq;

      const int k = (t.i & ncoulmask) >> ncoulshiftbits;

      double x2 = g2*rsq, a2 = 1.0/x2, t = r6inv*(1.0-factor_buck);

      x2 = a2*exp(-x2)*buck_c[itype][jtype];

      force_buck = buck1[itype][jtype]*r*expr-

               g8*(((6.0*a2+6.0)*a2+3.0)*a2+a2)*x2*rsq+t*buck2[itype][jtype];

               g8*(((6.0*a2+6.0)*a2+3.0)*a2+1.0)*x2*rsq+t*buck2[itype][jtype];

      eng += buck_a[itype][jtype]*expr-

        g6*((a2+1.0)*a2+0.5)*x2+t*buck_c[itype][jtype];

    }

    else {                                                // cut

    } else {                                                // cut

      force_buck =

        buck1[itype][jtype]*r*expr-factor_buck*buck_c[itype][jtype]*r6inv;

      eng += buck_a[itype][jtype]*expr-