subroutine mrseb(x,scale,mode,upv,dnv,usea,dsea,str,chm,bot,glu)
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
c                                                                    c
c  This program returns the fitted parton distributions for MRS(A)   c
c  ... it is an analytic approximation to the "grid version" and     c
c  gives much smoother distributions. It is, however, much slower.   c
c  Full details of the fit are contained in the preprint "Parton     c
c  "Distributions of the Proton", by A.D. Martin, R.G. Roberts and   c
c  W.J. Stirling, Phys. Rev. D50 (1994) 6734-6752, to which          c
c  reference should be made if appropriate.                          c  
c                                                                    c
cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
      implicit real*8(a-h,o-z)
      dimension z(18,8),f(8)
      data z/
     .2.029386, -1.892760,  0.478114,  0.538000,  0.044742,  0.058742,
     .3.956000, -0.136659, -0.513630, -0.389400,  1.267936,  0.134397,
     .5.132000, -0.235874,  0.939374, -0.008433,  0.833784,  0.376702,

     .0.295255, -0.169615,  0.028711,  0.330000,  0.174503, -0.045713,
     .4.706000, -0.536820,  0.114806,  5.029000, -0.322071,  0.949196,
     .5.561000, -2.161758, -1.334992, -0.002353,  1.134808, -0.156988,

     .0.775400,-0.517656,0.159759,-0.300000,0.049683,-0.098598,
     .5.300000,0.233708,0.282415,0.000000,-1.100596,0.052043,
     .5.200000,-3.232076,0.712254,0.003932,1.625446,-0.699441,

     .0.160750, -0.104311,  0.017157, -0.300000,  0.052451, -0.065844,
     .9.272000, -0.576575,  0.109982, -1.153000,  1.173228,  0.169775,
     .15.600000, -6.054861,  0.267608, -0.002159,  0.919959, -0.153501,

     .0.099280, -0.042174,  0.008380,  0.400000, -0.070009,  0.067714,
     .9.270000,  0.606514, -0.190625,  0.000000,  7.334181, -3.106807,
     .25.000000,-20.291985,  4.165453, -0.005437,  0.080749,  0.256036,

     .0.040260, -0.021695,  0.004481, -0.300000,  0.024073, -0.042711,
     .9.272000, -1.998587,  1.019307, -1.153000,  2.932868, -1.591815,
     .15.600000,-14.772277,  5.885859, -0.003502,  1.155235, -0.269042,

     .0.001753,  0.017854, -0.004894, -0.195549, -0.180373,  0.047210,
     .6.592858,  1.960693, -1.082506,  0.121744, -0.775791,  0.007846,
     .8.249182, -7.279327,  1.702087,  0.928112, -0.034017,  0.084953,

     .-0.004324,  0.012668, -0.001675, -0.276236,  0.090440, -0.112318,
     .2.647901,  3.239016, -0.534956,  1.390272, -2.629704,  0.646575,
     .-3.178775,  4.968992, -1.683463,  1.055388,  0.781798, -0.491059/

      al=0.23
      q2=scale*scale
      q0=2.
      arg=(dlog(scale/al)/dlog(q0/al))
      s=dlog(arg)

      do 10 j=1,8

      a=z(1,j)+z(2,j)*s+z(3,j)*s*s
      b=z(4,j)+z(5,j)*s+z(6,j)*s*s
      c=z(7,j)+z(8,j)*s+z(9,j)*s*s
      d=z(10,j)+z(11,j)*s+z(12,j)*s*s
      e=z(13,j)+z(14,j)*s+z(15,j)*s*s
      h=z(16,j)+z(17,j)*s+z(18,j)*s*s 
   10 f(j)=a*x**b*(1.-x)**c*(1.+d*sqrt(x)+e*x)*(dlog(1./x))**h
      upv=f(1)
      dnv=f(2)
      glu=f(3)
      dusum=f(4)
      dudif=f(5)
      str=f(6)
      chm=f(7)
      bot=f(8)
      dsea=0.5d0*(dusum+dudif)
      usea=0.5d0*(dusum-dudif)
      if(q2.lt.2.7d0) chm=0.d0
      if(q2.lt.30.d0) bot=0.d0
      if(chm.lt.0.d0) chm=0.d0
      if(bot.lt.0.d0) bot=0.d0
      return
      end