double complex function fagamma(i1,i2,i3,i4,i5,za,zb)
      implicit none
      include 'constants.f'
      include 'sprods_com.f'
      include 'zprods_decl.f'
      integer i1,i2,i3,i4,i5
      double complex L0,L1,Lsm1
      fagamma=
     . +za(i1,i3)**2/(za(i1,i5)*za(i3,i4)*za(i2,i5))
     . *Lsm1(-s(i2,i5),-s(i3,i4),-s(i1,i2),-s(i3,i4))
     . +0.5d0*za(i1,i2)*za(i3,i5)*zb(i4,i5)*zb(i2,i5)
     . /(za(i2,i5)*s(i1,i2)**2)*L1(-s(i3,i4),-s(i1,i2))
     . -1.5d0*za(i1,i3)*zb(i4,i5)/(za(i2,i5)*s(i1,i2))
     . *L0(-s(i3,i4),-s(i1,i2))
     . -0.5d0*zb(i2,i4)*zb(i4,i5)/(zb(i1,i2)*zb(i3,i4)*za(i2,i5))
      return
      end