(****************************************************************************************
 *
 * epsilon-expansion of Gauss hypergometric function with half-integer value of parameter
 * M.Kalmykov, JHEP 0604(2006)056 
 *
 ****************************************************************************************
 * F21A[a1_,a2_,f_,z_,ep_] is defined by Eq.(4.1)
 * F21B[a1_,a2_,f_,z_,ep_] is defined by Eq.(4.2)
 *
 * F21A[a1_,a2_,f_,z_,ep_] = Hypergeometric2F1[1+a1*ep,1+a2*ep,3/2+f*ep,z]
 * F21B[a1_,a2_,f_,z_,ep_] = Hypergeometric2F1[a1*ep,a2*ep,1/2+f*ep,z]
 *
 * "a1" and "a2" are the epsilon dependent part of upper values of parameters; 
 * "f" is the epsilon dependent part of down value value of parameter; 
 * "z" is argumant of hypergeometric function
 * "ep" is difference between dimention of space-time and integer values of parameters;
 * 
 * "y" is auxiliary variable defined by Eq.(4.3)
 *****************************************************************************************)


y[z_]:=( Sqrt[z-1]-Sqrt[z] )/( Sqrt[z-1]+Sqrt[z] ) 


   F21A[a1_,a2_,f_,z_,ep_]:= (1+2*f*ep)/(2*z)*(1-y)/(1+y)*
      (

       + Log[y]

       + ep * (  - 2*PolyLog[2, - y]*a1 - 2*PolyLog[2, - y]*a2 + 2*PolyLog[2,
          - y]*f - 2*PolyLog[2,y]*f - Zeta[2]*a1 - Zeta[2]*a2 + 3*Zeta[2]*f - 2
         *Log[y]*Log[1 - y]*f - 2*Log[y]*Log[1 + y]*a1 - 2*Log[y]*Log[1 + y]*a2
          + 2*Log[y]*Log[1 + y]*f + 1/2*Log[y]*Log[y]*a1 + 1/2*Log[y]*Log[y]*a2
          )


       + ep^2 * ( 8*PolyLog[1,2, - y]*a1*a2 - 12*PolyLog[1,2, - y]*a1*f + 4*
         PolyLog[1,2, - y]*a1^2 - 12*PolyLog[1,2, - y]*a2*f + 4*PolyLog[1,2, - 
         y]*a2^2 + 8*PolyLog[1,2, - y]*f^2 + 2*PolyLog[1,2,y^2]*a1*f + 2*
         PolyLog[1,2,y^2]*a2*f - 2*PolyLog[1,2,y^2]*f^2 - 4*PolyLog[1,2,y]*a1*f
          - 4*PolyLog[1,2,y]*a2*f + 8*PolyLog[1,2,y]*f^2 + 4*PolyLog[2, - y]*
         Log[1 - y]*a1*f + 4*PolyLog[2, - y]*Log[1 - y]*a2*f - 4*PolyLog[2, - y
         ]*Log[1 - y]*f^2 + 8*PolyLog[2, - y]*Log[1 + y]*a1*a2 - 8*PolyLog[2,
          - y]*Log[1 + y]*a1*f + 4*PolyLog[2, - y]*Log[1 + y]*a1^2 - 8*PolyLog[
         2, - y]*Log[1 + y]*a2*f + 4*PolyLog[2, - y]*Log[1 + y]*a2^2 + 4*
         PolyLog[2, - y]*Log[1 + y]*f^2 + 4*PolyLog[2,y]*Log[1 - y]*f^2 + 4*
         PolyLog[2,y]*Log[1 + y]*a1*f + 4*PolyLog[2,y]*Log[1 + y]*a2*f - 4*
         PolyLog[2,y]*Log[1 + y]*f^2 - 4*PolyLog[3, - y]*a1*a2 + 2*PolyLog[3,
          - y]*a1*f - 2*PolyLog[3, - y]*a1^2 + 2*PolyLog[3, - y]*a2*f - 2*
         PolyLog[3, - y]*a2^2 - 2*PolyLog[3,y]*a1*f - 2*PolyLog[3,y]*a2*f + 2*
         Zeta[2]*Log[1 - y]*a1*f + 2*Zeta[2]*Log[1 - y]*a2*f - 6*Zeta[2]*Log[1
          - y]*f^2 + 4*Zeta[2]*Log[1 + y]*a1*a2 - 8*Zeta[2]*Log[1 + y]*a1*f + 2
         *Zeta[2]*Log[1 + y]*a1^2 - 8*Zeta[2]*Log[1 + y]*a2*f + 2*Zeta[2]*Log[1
          + y]*a2^2 + 6*Zeta[2]*Log[1 + y]*f^2 - 2*Zeta[2]*Log[y]*a1*a2 + 3*
         Zeta[2]*Log[y]*a1*f - Zeta[2]*Log[y]*a1^2 + 3*Zeta[2]*Log[y]*a2*f - 
         Zeta[2]*Log[y]*a2^2 - 4*Zeta[3]*a1*a2 + 7*Zeta[3]*a1*f - 2*Zeta[3]*
         a1^2 + 7*Zeta[3]*a2*f - 2*Zeta[3]*a2^2 - 7*Zeta[3]*f^2 + 2*Log[y]*Log[
         1 - y]*Log[1 - y]*f^2 + 4*Log[y]*Log[1 - y]*Log[1 + y]*a1*f + 4*Log[y]
         *Log[1 - y]*Log[1 + y]*a2*f - 4*Log[y]*Log[1 - y]*Log[1 + y]*f^2 + 4*
         Log[y]*Log[1 + y]*Log[1 + y]*a1*a2 - 4*Log[y]*Log[1 + y]*Log[1 + y]*a1
         *f + 2*Log[y]*Log[1 + y]*Log[1 + y]*a1^2 - 4*Log[y]*Log[1 + y]*Log[1
          + y]*a2*f + 2*Log[y]*Log[1 + y]*Log[1 + y]*a2^2 + 2*Log[y]*Log[1 + y]
         *Log[1 + y]*f^2 - Log[y]*Log[y]*Log[1 - y]*a1*f - Log[y]*Log[y]*Log[1
          - y]*a2*f - 2*Log[y]*Log[y]*Log[1 + y]*a1*a2 + Log[y]*Log[y]*Log[1 + 
         y]*a1*f - Log[y]*Log[y]*Log[1 + y]*a1^2 + Log[y]*Log[y]*Log[1 + y]*a2*
         f - Log[y]*Log[y]*Log[1 + y]*a2^2 + 1/6*Log[y]*Log[y]*Log[y]*a1*a2 + 1/
         6*Log[y]*Log[y]*Log[y]*a1^2 + 1/6*Log[y]*Log[y]*Log[y]*a2^2 )


       + ep^3 * ( 48*PolyLog[1,2, - y]*Log[1 + y]*a1*a2*f - 24*PolyLog[1,2, - y
         ]*Log[1 + y]*a1*a2^2 - 16*PolyLog[1,2, - y]*Log[1 + y]*a1*f^2 - 24*
         PolyLog[1,2, - y]*Log[1 + y]*a1^2*a2 + 24*PolyLog[1,2, - y]*Log[1 + y]
         *a1^2*f - 8*PolyLog[1,2, - y]*Log[1 + y]*a1^3 - 16*PolyLog[1,2, - y]*
         Log[1 + y]*a2*f^2 + 24*PolyLog[1,2, - y]*Log[1 + y]*a2^2*f - 8*
         PolyLog[1,2, - y]*Log[1 + y]*a2^3 - 4*PolyLog[1,2,y^2]*Log[1 - y]*a1*
         a2*f + 2*PolyLog[1,2,y^2]*Log[1 - y]*a1*f^2 - 2*PolyLog[1,2,y^2]*Log[1
          - y]*a1^2*f + 2*PolyLog[1,2,y^2]*Log[1 - y]*a2*f^2 - 2*PolyLog[1,2,
         y^2]*Log[1 - y]*a2^2*f - 4*PolyLog[1,2,y^2]*Log[1 + y]*a1*a2*f + 2*
         PolyLog[1,2,y^2]*Log[1 + y]*a1*f^2 - 2*PolyLog[1,2,y^2]*Log[1 + y]*
         a1^2*f + 2*PolyLog[1,2,y^2]*Log[1 + y]*a2*f^2 - 2*PolyLog[1,2,y^2]*
         Log[1 + y]*a2^2*f + 16*PolyLog[1,2,y]*Log[1 - y]*a1*a2*f - 16*PolyLog[
         1,2,y]*Log[1 - y]*a1*f^2 + 8*PolyLog[1,2,y]*Log[1 - y]*a1^2*f - 16*
         PolyLog[1,2,y]*Log[1 - y]*a2*f^2 + 8*PolyLog[1,2,y]*Log[1 - y]*a2^2*f
          + 48*PolyLog[1,3, - y]*a1*a2*f - 24*PolyLog[1,3, - y]*a1*a2^2 - 16*
         PolyLog[1,3, - y]*a1*f^2 - 24*PolyLog[1,3, - y]*a1^2*a2 + 24*PolyLog[1
         ,3, - y]*a1^2*f - 8*PolyLog[1,3, - y]*a1^3 - 16*PolyLog[1,3, - y]*a2*
         f^2 + 24*PolyLog[1,3, - y]*a2^2*f - 8*PolyLog[1,3, - y]*a2^3 - 4*
         PolyLog[1,3,y^2]*a1*a2*f + 2*PolyLog[1,3,y^2]*a1*f^2 - 2*PolyLog[1,3,
         y^2]*a1^2*f + 2*PolyLog[1,3,y^2]*a2*f^2 - 2*PolyLog[1,3,y^2]*a2^2*f + 
         16*PolyLog[1,3,y]*a1*a2*f - 16*PolyLog[1,3,y]*a1*f^2 + 8*PolyLog[1,3,y
         ]*a1^2*f - 16*PolyLog[1,3,y]*a2*f^2 + 8*PolyLog[1,3,y]*a2^2*f - 4*
         PolyLog[2, - y]*Log[1 - y]*Log[1 - y]*a1*a2*f + 2*PolyLog[2, - y]*Log[
         1 - y]*Log[1 - y]*a1*f^2 - 2*PolyLog[2, - y]*Log[1 - y]*Log[1 - y]*
         a1^2*f + 2*PolyLog[2, - y]*Log[1 - y]*Log[1 - y]*a2*f^2 - 2*PolyLog[2,
          - y]*Log[1 - y]*Log[1 - y]*a2^2*f - 8*PolyLog[2, - y]*Log[1 - y]*Log[
         1 + y]*a1*a2*f + 4*PolyLog[2, - y]*Log[1 - y]*Log[1 + y]*a1*f^2 - 4*
         PolyLog[2, - y]*Log[1 - y]*Log[1 + y]*a1^2*f + 4*PolyLog[2, - y]*Log[1
          - y]*Log[1 + y]*a2*f^2 - 4*PolyLog[2, - y]*Log[1 - y]*Log[1 + y]*a2^2
         *f + 20*PolyLog[2, - y]*Log[1 + y]*Log[1 + y]*a1*a2*f - 12*PolyLog[2,
          - y]*Log[1 + y]*Log[1 + y]*a1*a2^2 - 6*PolyLog[2, - y]*Log[1 + y]*
         Log[1 + y]*a1*f^2 - 12*PolyLog[2, - y]*Log[1 + y]*Log[1 + y]*a1^2*a2
          + 10*PolyLog[2, - y]*Log[1 + y]*Log[1 + y]*a1^2*f - 4*PolyLog[2, - y]
         *Log[1 + y]*Log[1 + y]*a1^3 - 6*PolyLog[2, - y]*Log[1 + y]*Log[1 + y]*
         a2*f^2 + 10*PolyLog[2, - y]*Log[1 + y]*Log[1 + y]*a2^2*f - 4*PolyLog[2
         , - y]*Log[1 + y]*Log[1 + y]*a2^3 - PolyLog[2, - y]*Log[y]*Log[y]*a1*
         a2*f + PolyLog[2, - y]*Log[y]*Log[y]*a1*a2^2 + PolyLog[2, - y]*Log[y]*
         Log[y]*a1^2*a2 + 4*PolyLog[2,y]*Log[1 - y]*Log[1 - y]*a1*a2*f - 6*
         PolyLog[2,y]*Log[1 - y]*Log[1 - y]*a1*f^2 + 2*PolyLog[2,y]*Log[1 - y]*
         Log[1 - y]*a1^2*f - 6*PolyLog[2,y]*Log[1 - y]*Log[1 - y]*a2*f^2 + 2*
         PolyLog[2,y]*Log[1 - y]*Log[1 - y]*a2^2*f - 8*PolyLog[2,y]*Log[1 - y]*
         Log[1 + y]*a1*a2*f + 4*PolyLog[2,y]*Log[1 - y]*Log[1 + y]*a1*f^2 - 4*
         PolyLog[2,y]*Log[1 - y]*Log[1 + y]*a1^2*f + 4*PolyLog[2,y]*Log[1 - y]*
         Log[1 + y]*a2*f^2 - 4*PolyLog[2,y]*Log[1 - y]*Log[1 + y]*a2^2*f - 4*
         PolyLog[2,y]*Log[1 + y]*Log[1 + y]*a1*a2*f + 2*PolyLog[2,y]*Log[1 + y]
         *Log[1 + y]*a1*f^2 - 2*PolyLog[2,y]*Log[1 + y]*Log[1 + y]*a1^2*f + 2*
         PolyLog[2,y]*Log[1 + y]*Log[1 + y]*a2*f^2 - 2*PolyLog[2,y]*Log[1 + y]*
         Log[1 + y]*a2^2*f + PolyLog[2,y]*Log[y]*Log[y]*a1*a2*f - 24*PolyLog[2,
         2, - y]*a1*a2*f + 12*PolyLog[2,2, - y]*a1*a2^2 + 8*PolyLog[2,2, - y]*
         a1*f^2 + 12*PolyLog[2,2, - y]*a1^2*a2 - 12*PolyLog[2,2, - y]*a1^2*f + 
         4*PolyLog[2,2, - y]*a1^3 + 8*PolyLog[2,2, - y]*a2*f^2 - 12*PolyLog[2,2
         , - y]*a2^2*f + 4*PolyLog[2,2, - y]*a2^3 + 2*PolyLog[2,2,y^2]*a1*a2*f
          - PolyLog[2,2,y^2]*a1*f^2 + PolyLog[2,2,y^2]*a1^2*f - PolyLog[2,2,y^2
         ]*a2*f^2 + PolyLog[2,2,y^2]*a2^2*f - 8*PolyLog[2,2,y]*a1*a2*f + 8*
         PolyLog[2,2,y]*a1*f^2 - 4*PolyLog[2,2,y]*a1^2*f + 8*PolyLog[2,2,y]*a2*
         f^2 - 4*PolyLog[2,2,y]*a2^2*f + 8*PolyLog[3, - y]*Log[1 - y]*a1*a2*f
          - 4*PolyLog[3, - y]*Log[1 - y]*a1*f^2 + 4*PolyLog[3, - y]*Log[1 - y]*
         a1^2*f - 4*PolyLog[3, - y]*Log[1 - y]*a2*f^2 + 4*PolyLog[3, - y]*Log[1
          - y]*a2^2*f - 16*PolyLog[3, - y]*Log[1 + y]*a1*a2*f + 12*PolyLog[3,
          - y]*Log[1 + y]*a1*a2^2 + 4*PolyLog[3, - y]*Log[1 + y]*a1*f^2 + 12*
         PolyLog[3, - y]*Log[1 + y]*a1^2*a2 - 8*PolyLog[3, - y]*Log[1 + y]*a1^2
         *f + 4*PolyLog[3, - y]*Log[1 + y]*a1^3 + 4*PolyLog[3, - y]*Log[1 + y]*
         a2*f^2 - 8*PolyLog[3, - y]*Log[1 + y]*a2^2*f + 4*PolyLog[3, - y]*Log[1
          + y]*a2^3 + 4*PolyLog[3, - y]*Log[y]*a1*a2*f - 4*PolyLog[3, - y]*Log[
         y]*a1*a2^2 - 4*PolyLog[3, - y]*Log[y]*a1^2*a2 + 4*PolyLog[3,y]*Log[1
          - y]*a1*f^2 + 4*PolyLog[3,y]*Log[1 - y]*a2*f^2 + 8*PolyLog[3,y]*Log[1
          + y]*a1*a2*f - 4*PolyLog[3,y]*Log[1 + y]*a1*f^2 + 4*PolyLog[3,y]*Log[
         1 + y]*a1^2*f - 4*PolyLog[3,y]*Log[1 + y]*a2*f^2 + 4*PolyLog[3,y]*Log[
         1 + y]*a2^2*f - 4*PolyLog[3,y]*Log[y]*a1*a2*f - 4*PolyLog[4, - y]*a1*
         a2*f + 2*PolyLog[4, - y]*a1*a2^2 + 2*PolyLog[4, - y]*a1^2*a2 + 2*
         PolyLog[4, - y]*a1^2*f - 2*PolyLog[4, - y]*a1^3 + 2*PolyLog[4, - y]*
         a2^2*f - 2*PolyLog[4, - y]*a2^3 - 8*PolyLog[4, - (1-y)/(1+y)]*a1*
         a2*f + 12*PolyLog[4, - (1-y)/(1+y)]*a1*f^2 - 4*PolyLog[4, - (1-y)/(1+y)]*
         a1^2*f + 12*PolyLog[4, - (1-y)/(1+y)]*a2*f^2 - 4*
         PolyLog[4, - (1-y)/(1+y)]*a2^2*f - 8*PolyLog[4, - (1-y)/(1+y)]*f^3 
         + 8*PolyLog[4,(1-y)/(1+y)]*a1*a2*f - 12*PolyLog[4,(1-y)/(1+y)]*a1*f^2 
         + 4*PolyLog[4,(1-y)/(1+y)]*a1^2*f - 12*
         PolyLog[4,(1-y)/(1+y)]*a2*f^2 + 4*PolyLog[4,(1-y)/(1+y)]*
         a2^2*f + 8*PolyLog[4,(1-y)/(1+y)]*f^3 + 4*PolyLog[4,y]*a1*a2*f - 
         2*PolyLog[4,y]*a1^2*f - 2*PolyLog[4,y]*a2^2*f - 6*Zeta[2]*Log[1 - y]*
         Log[1 - y]*a1*a2*f + 7*Zeta[2]*Log[1 - y]*Log[1 - y]*a1*f^2 - 3*Zeta[2
         ]*Log[1 - y]*Log[1 - y]*a1^2*f + 7*Zeta[2]*Log[1 - y]*Log[1 - y]*a2*
         f^2 - 3*Zeta[2]*Log[1 - y]*Log[1 - y]*a2^2*f + 4*Zeta[2]*Log[1 - y]*
         Log[1 + y]*a1*a2*f - 2*Zeta[2]*Log[1 - y]*Log[1 + y]*a1*f^2 + 2*Zeta[2
         ]*Log[1 - y]*Log[1 + y]*a1^2*f - 2*Zeta[2]*Log[1 - y]*Log[1 + y]*a2*
         f^2 + 2*Zeta[2]*Log[1 - y]*Log[1 + y]*a2^2*f + 14*Zeta[2]*Log[1 + y]*
         Log[1 + y]*a1*a2*f - 6*Zeta[2]*Log[1 + y]*Log[1 + y]*a1*a2^2 - 5*Zeta[
         2]*Log[1 + y]*Log[1 + y]*a1*f^2 - 6*Zeta[2]*Log[1 + y]*Log[1 + y]*a1^2
         *a2 + 7*Zeta[2]*Log[1 + y]*Log[1 + y]*a1^2*f - 2*Zeta[2]*Log[1 + y]*
         Log[1 + y]*a1^3 - 5*Zeta[2]*Log[1 + y]*Log[1 + y]*a2*f^2 + 7*Zeta[2]*
         Log[1 + y]*Log[1 + y]*a2^2*f - 2*Zeta[2]*Log[1 + y]*Log[1 + y]*a2^3 + 
         4*Zeta[2]*Log[y]*Log[1 - y]*a1*a2*f - 6*Zeta[2]*Log[y]*Log[1 - y]*a1*
         f^2 + 2*Zeta[2]*Log[y]*Log[1 - y]*a1^2*f - 6*Zeta[2]*Log[y]*Log[1 - y]
         *a2*f^2 + 2*Zeta[2]*Log[y]*Log[1 - y]*a2^2*f - 16*Zeta[2]*Log[y]*Log[1
          + y]*a1*a2*f + 6*Zeta[2]*Log[y]*Log[1 + y]*a1*a2^2 + 6*Zeta[2]*Log[y]
         *Log[1 + y]*a1*f^2 + 6*Zeta[2]*Log[y]*Log[1 + y]*a1^2*a2 - 8*Zeta[2]*
         Log[y]*Log[1 + y]*a1^2*f + 2*Zeta[2]*Log[y]*Log[1 + y]*a1^3 + 6*Zeta[2
         ]*Log[y]*Log[1 + y]*a2*f^2 - 8*Zeta[2]*Log[y]*Log[1 + y]*a2^2*f + 2*
         Zeta[2]*Log[y]*Log[1 + y]*a2^3 + 3/2*Zeta[2]*Log[y]*Log[y]*a1*a2*f - 
         Zeta[2]*Log[y]*Log[y]*a1*a2^2 - Zeta[2]*Log[y]*Log[y]*a1^2*a2 + 3/2*
         Zeta[2]*Log[y]*Log[y]*a1^2*f - 1/2*Zeta[2]*Log[y]*Log[y]*a1^3 + 3/2*
         Zeta[2]*Log[y]*Log[y]*a2^2*f - 1/2*Zeta[2]*Log[y]*Log[y]*a2^3 - 6*
         Zeta[3]*Log[1 - y]*a1*a2*f + 7*Zeta[3]*Log[1 - y]*a1*f^2 - 3*Zeta[3]*
         Log[1 - y]*a1^2*f + 7*Zeta[3]*Log[1 - y]*a2*f^2 - 3*Zeta[3]*Log[1 - y]
         *a2^2*f - 22*Zeta[3]*Log[1 + y]*a1*a2*f + 12*Zeta[3]*Log[1 + y]*a1*
         a2^2 + 7*Zeta[3]*Log[1 + y]*a1*f^2 + 12*Zeta[3]*Log[1 + y]*a1^2*a2 - 
         11*Zeta[3]*Log[1 + y]*a1^2*f + 4*Zeta[3]*Log[1 + y]*a1^3 + 7*Zeta[3]*
         Log[1 + y]*a2*f^2 - 11*Zeta[3]*Log[1 + y]*a2^2*f + 4*Zeta[3]*Log[1 + y
         ]*a2^3 + 7*Zeta[3]*Log[y]*a1*a2*f - 3*Zeta[3]*Log[y]*a1*a2^2 - 7*Zeta[
         3]*Log[y]*a1*f^2 - 3*Zeta[3]*Log[y]*a1^2*a2 + 7*Zeta[3]*Log[y]*a1^2*f
          - 2*Zeta[3]*Log[y]*a1^3 - 7*Zeta[3]*Log[y]*a2*f^2 + 7*Zeta[3]*Log[y]*
         a2^2*f - 2*Zeta[3]*Log[y]*a2^3 - 15*Zeta[4]*a1*a2*f + 1/4*Zeta[4]*a1*
         a2^2 + 45/4*Zeta[4]*a1*f^2 + 1/4*Zeta[4]*a1^2*a2 - 9/4*Zeta[4]*a1^3 + 
         45/4*Zeta[4]*a2*f^2 - 9/4*Zeta[4]*a2^3 + 4/3*Log[y]*Log[1 - y]*Log[1
          - y]*Log[1 - y]*a1*a2*f - 2*Log[y]*Log[1 - y]*Log[1 - y]*Log[1 - y]*
         a1*f^2 + 2/3*Log[y]*Log[1 - y]*Log[1 - y]*Log[1 - y]*a1^2*f - 2*Log[y]
         *Log[1 - y]*Log[1 - y]*Log[1 - y]*a2*f^2 + 2/3*Log[y]*Log[1 - y]*Log[1
          - y]*Log[1 - y]*a2^2*f - 4*Log[y]*Log[1 - y]*Log[1 - y]*Log[1 + y]*a1
         *a2*f + 2*Log[y]*Log[1 - y]*Log[1 - y]*Log[1 + y]*a1*f^2 - 2*Log[y]*
         Log[1 - y]*Log[1 - y]*Log[1 + y]*a1^2*f + 2*Log[y]*Log[1 - y]*Log[1 - 
         y]*Log[1 + y]*a2*f^2 - 2*Log[y]*Log[1 - y]*Log[1 - y]*Log[1 + y]*a2^2*
         f - 4*Log[y]*Log[1 - y]*Log[1 + y]*Log[1 + y]*a1*a2*f + 2*Log[y]*Log[1
          - y]*Log[1 + y]*Log[1 + y]*a1*f^2 - 2*Log[y]*Log[1 - y]*Log[1 + y]*
         Log[1 + y]*a1^2*f + 2*Log[y]*Log[1 - y]*Log[1 + y]*Log[1 + y]*a2*f^2
          - 2*Log[y]*Log[1 - y]*Log[1 + y]*Log[1 + y]*a2^2*f + 20/3*Log[y]*Log[
         1 + y]*Log[1 + y]*Log[1 + y]*a1*a2*f - 4*Log[y]*Log[1 + y]*Log[1 + y]*
         Log[1 + y]*a1*a2^2 - 2*Log[y]*Log[1 + y]*Log[1 + y]*Log[1 + y]*a1*f^2
          - 4*Log[y]*Log[1 + y]*Log[1 + y]*Log[1 + y]*a1^2*a2 + 10/3*Log[y]*
         Log[1 + y]*Log[1 + y]*Log[1 + y]*a1^2*f - 4/3*Log[y]*Log[1 + y]*Log[1
          + y]*Log[1 + y]*a1^3 - 2*Log[y]*Log[1 + y]*Log[1 + y]*Log[1 + y]*a2*
         f^2 + 10/3*Log[y]*Log[1 + y]*Log[1 + y]*Log[1 + y]*a2^2*f - 4/3*Log[y]
         *Log[1 + y]*Log[1 + y]*Log[1 + y]*a2^3 + Log[y]*Log[y]*Log[1 - y]*Log[
         1 - y]*a1*f^2 + Log[y]*Log[y]*Log[1 - y]*Log[1 - y]*a2*f^2 + 4*Log[y]*
         Log[y]*Log[1 - y]*Log[1 + y]*a1*a2*f - 2*Log[y]*Log[y]*Log[1 - y]*Log[
         1 + y]*a1*f^2 + 2*Log[y]*Log[y]*Log[1 - y]*Log[1 + y]*a1^2*f - 2*Log[y
         ]*Log[y]*Log[1 - y]*Log[1 + y]*a2*f^2 + 2*Log[y]*Log[y]*Log[1 - y]*
         Log[1 + y]*a2^2*f - 4*Log[y]*Log[y]*Log[1 + y]*Log[1 + y]*a1*a2*f + 3*
         Log[y]*Log[y]*Log[1 + y]*Log[1 + y]*a1*a2^2 + Log[y]*Log[y]*Log[1 + y]
         *Log[1 + y]*a1*f^2 + 3*Log[y]*Log[y]*Log[1 + y]*Log[1 + y]*a1^2*a2 - 2
         *Log[y]*Log[y]*Log[1 + y]*Log[1 + y]*a1^2*f + Log[y]*Log[y]*Log[1 + y]
         *Log[1 + y]*a1^3 + Log[y]*Log[y]*Log[1 + y]*Log[1 + y]*a2*f^2 - 2*Log[
         y]*Log[y]*Log[1 + y]*Log[1 + y]*a2^2*f + Log[y]*Log[y]*Log[1 + y]*Log[
         1 + y]*a2^3 - 1/3*Log[y]*Log[y]*Log[y]*Log[1 - y]*a1*a2*f - 1/3*Log[y]
         *Log[y]*Log[y]*Log[1 - y]*a1^2*f - 1/3*Log[y]*Log[y]*Log[y]*Log[1 - y]
         *a2^2*f + 1/3*Log[y]*Log[y]*Log[y]*Log[1 + y]*a1*a2*f - 2/3*Log[y]*
         Log[y]*Log[y]*Log[1 + y]*a1*a2^2 - 2/3*Log[y]*Log[y]*Log[y]*Log[1 + y]
         *a1^2*a2 + 1/3*Log[y]*Log[y]*Log[y]*Log[1 + y]*a1^2*f - 1/3*Log[y]*
         Log[y]*Log[y]*Log[1 + y]*a1^3 + 1/3*Log[y]*Log[y]*Log[y]*Log[1 + y]*
         a2^2*f - 1/3*Log[y]*Log[y]*Log[y]*Log[1 + y]*a2^3 + 1/24*Log[y]*Log[y]
         *Log[y]*Log[y]*a1*a2^2 + 1/24*Log[y]*Log[y]*Log[y]*Log[y]*a1^2*a2 + 1/
         24*Log[y]*Log[y]*Log[y]*Log[y]*a1^3 + 1/24*Log[y]*Log[y]*Log[y]*Log[y]
         *a2^3 )

       + ep^4 * F21A
       ) 




   F21B[a1_,a2_,f_,z_,ep_]:= 1 + a1*a2*ep^2*
      (

       - 1/2*Log[y]*Log[y]

       + ep * (  - 2*PolyLog[2, - y]*Log[y]*a1 - 2*PolyLog[2, - y]*Log[y]*a2 + 
         2*PolyLog[2, - y]*Log[y]*f - 2*PolyLog[2,y]*Log[y]*f + 4*PolyLog[3, - 
         y]*a1 + 4*PolyLog[3, - y]*a2 - 4*PolyLog[3, - y]*f + 4*PolyLog[3,y]*f
          + Zeta[2]*Log[y]*a1 + Zeta[2]*Log[y]*a2 - 3*Zeta[2]*Log[y]*f + 3*
         Zeta[3]*a1 + 3*Zeta[3]*a2 - 7*Zeta[3]*f - 1/6*Log[y]*Log[y]*Log[y]*a1
          - 1/6*Log[y]*Log[y]*Log[y]*a2 )

       + ep^2 * (  - 8*PolyLog[1,2, - y]*Log[y]*a1*a2 + 12*PolyLog[1,2, - y]*
         Log[y]*a1*f - 4*PolyLog[1,2, - y]*Log[y]*a1^2 + 12*PolyLog[1,2, - y]*
         Log[y]*a2*f - 4*PolyLog[1,2, - y]*Log[y]*a2^2 - 8*PolyLog[1,2, - y]*
         Log[y]*f^2 - 2*PolyLog[1,2,y^2]*Log[y]*a1*f - 2*PolyLog[1,2,y^2]*Log[y
         ]*a2*f + 2*PolyLog[1,2,y^2]*Log[y]*f^2 + 4*PolyLog[1,2,y]*Log[y]*a1*f
          + 4*PolyLog[1,2,y]*Log[y]*a2*f - 8*PolyLog[1,2,y]*Log[y]*f^2 + 4*
         PolyLog[2, - y]*PolyLog[2, - y]*a1*a2 - 4*PolyLog[2, - y]*PolyLog[2,
          - y]*a1*f + 2*PolyLog[2, - y]*PolyLog[2, - y]*a1^2 - 4*PolyLog[2, - y
         ]*PolyLog[2, - y]*a2*f + 2*PolyLog[2, - y]*PolyLog[2, - y]*a2^2 + 2*
         PolyLog[2, - y]*PolyLog[2, - y]*f^2 + 4*PolyLog[2, - y]*Zeta[2]*a1*a2
          - 8*PolyLog[2, - y]*Zeta[2]*a1*f + 2*PolyLog[2, - y]*Zeta[2]*a1^2 - 8
         *PolyLog[2, - y]*Zeta[2]*a2*f + 2*PolyLog[2, - y]*Zeta[2]*a2^2 + 6*
         PolyLog[2, - y]*Zeta[2]*f^2 - 2*PolyLog[2, - y]*Log[y]*Log[y]*a1*a2 + 
         PolyLog[2, - y]*Log[y]*Log[y]*a1*f - PolyLog[2, - y]*Log[y]*Log[y]*
         a1^2 + PolyLog[2, - y]*Log[y]*Log[y]*a2*f - PolyLog[2, - y]*Log[y]*
         Log[y]*a2^2 + 4*PolyLog[2,y]*PolyLog[2, - y]*a1*f + 4*PolyLog[2,y]*
         PolyLog[2, - y]*a2*f - 4*PolyLog[2,y]*PolyLog[2, - y]*f^2 + 2*PolyLog[
         2,y]*PolyLog[2,y]*f^2 + 2*PolyLog[2,y]*Zeta[2]*a1*f + 2*PolyLog[2,y]*
         Zeta[2]*a2*f - 6*PolyLog[2,y]*Zeta[2]*f^2 - PolyLog[2,y]*Log[y]*Log[y]
         *a1*f - PolyLog[2,y]*Log[y]*Log[y]*a2*f + 4*PolyLog[3, - y]*Log[y]*a1*
         a2 - 2*PolyLog[3, - y]*Log[y]*a1*f + 2*PolyLog[3, - y]*Log[y]*a1^2 - 2
         *PolyLog[3, - y]*Log[y]*a2*f + 2*PolyLog[3, - y]*Log[y]*a2^2 + 2*
         PolyLog[3,y]*Log[y]*a1*f + 2*PolyLog[3,y]*Log[y]*a2*f + Zeta[2]*Log[y]
         *Log[y]*a1*a2 - 3/2*Zeta[2]*Log[y]*Log[y]*a1*f + 1/2*Zeta[2]*Log[y]*
         Log[y]*a1^2 - 3/2*Zeta[2]*Log[y]*Log[y]*a2*f + 1/2*Zeta[2]*Log[y]*Log[
         y]*a2^2 + 4*Zeta[3]*Log[y]*a1*a2 - 7*Zeta[3]*Log[y]*a1*f + 2*Zeta[3]*
         Log[y]*a1^2 - 7*Zeta[3]*Log[y]*a2*f + 2*Zeta[3]*Log[y]*a2^2 + 7*Zeta[3
         ]*Log[y]*f^2 + 5/2*Zeta[4]*a1*a2 - 15/2*Zeta[4]*a1*f + 5/4*Zeta[4]*
         a1^2 - 15/2*Zeta[4]*a2*f + 5/4*Zeta[4]*a2^2 + 45/4*Zeta[4]*f^2 - 1/24*
         Log[y]*Log[y]*Log[y]*Log[y]*a1*a2 - 1/24*Log[y]*Log[y]*Log[y]*Log[y]*
         a1^2 - 1/24*Log[y]*Log[y]*Log[y]*Log[y]*a2^2 )

       + ep^3 * F21B
       )

