subroutine mrstlo(x,q2,mode,upv,dnv,usea,dsea,str,chm,bot,glu) C***************************************************************C C C C This is a package for the new MRST 2001 LO parton C C distributions. C C Reference: A.D. Martin, R.G. Roberts, W.J. Stirling and C C R.S. Thorne, hep-ph/0201xxx C C C C There is 1 pdf set corresponding to mode = 1 C C C C Mode=1 gives the default set with Lambda(MSbar,nf=4) = 0.220 C C corresponding to alpha_s(M_Z) of 0.130 C C This set reads a grid whose first number is 0.02868 C C C C This subroutine uses an improved interpolation procedure C C for extracting values of the pdf's from the grid C C C C Comments to : W.J.Stirling@durham.ac.uk C C C C***************************************************************C implicit real*8(a-h,o-z) character*128 mfile common/mrinput/mfile data xmin,xmax,qsqmin,qsqmax/1d-5,1d0,1.25d0,1d7/ if(q2.lt.qsqmin.or.q2.gt.qsqmax) print 99,q2 if(x.lt.xmin.or.x.gt.xmax) print 98,x if(mode.eq.1) then call mrst1(x,q2,upv,dnv,usea,dsea,str,chm,bot,glu) endif 99 format(' WARNING: Q^2 VALUE IS OUT OF RANGE ','q2= ',e10.5) 98 format(' WARNING: X VALUE IS OUT OF RANGE ','x= ',e10.5) return end subroutine mrst1(x,qsq,upv,dnv,usea,dsea,str,chm,bot,glu) implicit real*8(a-h,o-z) parameter(nx=49,nq=37,np=8,nqc0=2,nqb0=11,nqc=35,nqb=26) real*8 f1(nx,nq),f2(nx,nq),f3(nx,nq),f4(nx,nq),f5(nx,nq), .f6(nx,nq),f7(nx,nq),f8(nx,nq),fc(nx,nqc),fb(nx,nqb) real*8 qq(nq),xx(nx),cc1(nx,nq,4,4),cc2(nx,nq,4,4), .cc3(nx,nq,4,4),cc4(nx,nq,4,4),cc6(nx,nq,4,4),cc8(nx,nq,4,4), .ccc(nx,nqc,4,4),ccb(nx,nqb,4,4) real*8 xxl(nx),qql(nq),qqlc(nqc),qqlb(nqb) character*128 mfile common/mrinput/mfile data xx/1d-5,2d-5,4d-5,6d-5,8d-5, . 1d-4,2d-4,4d-4,6d-4,8d-4, . 1d-3,2d-3,4d-3,6d-3,8d-3, . 1d-2,1.4d-2,2d-2,3d-2,4d-2,6d-2,8d-2, . .1d0,.125d0,.15d0,.175d0,.2d0,.225d0,.25d0,.275d0, . .3d0,.325d0,.35d0,.375d0,.4d0,.425d0,.45d0,.475d0, . .5d0,.525d0,.55d0,.575d0,.6d0,.65d0,.7d0,.75d0, . .8d0,.9d0,1d0/ data qq/1.25d0,1.5d0,2d0,2.5d0,3.2d0,4d0,5d0,6.4d0,8d0,1d1, . 1.2d1,1.8d1,2.6d1,4d1,6.4d1,1d2, . 1.6d2,2.4d2,4d2,6.4d2,1d3,1.8d3,3.2d3,5.6d3,1d4, . 1.8d4,3.2d4,5.6d4,1d5,1.8d5,3.2d5,5.6d5,1d6, . 1.8d6,3.2d6,5.6d6,1d7/ data xmin,xmax,qsqmin,qsqmax/1d-5,1d0,1.25d0,1d7/ data init/0/ save xsave=x q2save=qsq if(init.ne.0) goto 10 open(unit=33,file=mfile,status='old') do 20 n=1,nx-1 do 20 m=1,nq read(33,50)f1(n,m),f2(n,m),f3(n,m),f4(n,m), . f5(n,m),f7(n,m),f6(n,m),f8(n,m) c notation: 1=uval 2=dval 3=glue 4=usea 5=chm 6=str 7=btm 8=dsea 20 continue do 40 m=1,nq f1(nx,m)=0.d0 f2(nx,m)=0.d0 f3(nx,m)=0.d0 f4(nx,m)=0.d0 f5(nx,m)=0.d0 f6(nx,m)=0.d0 f7(nx,m)=0.d0 f8(nx,m)=0.d0 40 continue do n=1,nx xxl(n)=dlog(xx(n)) enddo do m=1,nq qql(m)=dlog(qq(m)) enddo call jeppe1(nx,nq,xxl,qql,f1,cc1) call jeppe1(nx,nq,xxl,qql,f2,cc2) call jeppe1(nx,nq,xxl,qql,f3,cc3) call jeppe1(nx,nq,xxl,qql,f4,cc4) call jeppe1(nx,nq,xxl,qql,f6,cc6) call jeppe1(nx,nq,xxl,qql,f8,cc8) emc2=2.045 emb2=18.5 do 44 m=1,nqc qqlc(m)=qql(m+nqc0) do 44 n=1,nx fc(n,m)=f5(n,m+nqc0) 44 continue qqlc(1)=dlog(emc2) call jeppe1(nx,nqc,xxl,qqlc,fc,ccc) do 45 m=1,nqb qqlb(m)=qql(m+nqb0) do 45 n=1,nx fb(n,m)=f7(n,m+nqb0) 45 continue qqlb(1)=dlog(emb2) call jeppe1(nx,nqb,xxl,qqlb,fb,ccb) init=1 10 continue xlog=dlog(x) qsqlog=dlog(qsq) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc1,upv) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc2,dnv) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc3,glu) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc4,usea) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc6,str) call jeppe2(xlog,qsqlog,nx,nq,xxl,qql,cc8,dsea) chm=0.d0 if(qsq.gt.emc2) then call jeppe2(xlog,qsqlog,nx,nqc,xxl,qqlc,ccc,chm) endif bot=0.d0 if(qsq.gt.emb2) then call jeppe2(xlog,qsqlog,nx,nqb,xxl,qqlb,ccb,bot) endif x=xsave qsq=q2save return 50 format(8f10.5) end c subroutine jeppe1(nx,my,xx,yy,ff,cc) c implicit real*8(a-h,o-z) c dimension xx(nx),yy(my),ff(nx,my),ff1(nx,my),ff2(nx,my), c xff12(nx,my),yy0(4),yy1(4),yy2(4),yy12(4),z(16),wt(16,16), c xcl(16),cc(nx,my,4,4),iwt(16,16) subroutine jeppe1(nx,my,xx,yy,ff,cc) implicit real*8(a-h,o-z) PARAMETER(NNX=49,MMY=37) dimension xx(nx),yy(my),ff(nx,my),ff1(NNX,MMY),ff2(NNX,MMY), xff12(NNX,MMY),yy0(4),yy1(4),yy2(4),yy12(4),z(16),wt(16,16), xcl(16),cc(nx,my,4,4),iwt(16,16) data iwt/1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, x 0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0, x -3,0,0,3,0,0,0,0,-2,0,0,-1,0,0,0,0, x 2,0,0,-2,0,0,0,0,1,0,0,1,0,0,0,0, x 0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0, x 0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0, x 0,0,0,0,-3,0,0,3,0,0,0,0,-2,0,0,-1, x 0,0,0,0,2,0,0,-2,0,0,0,0,1,0,0,1, x -3,3,0,0,-2,-1,0,0,0,0,0,0,0,0,0,0, x 0,0,0,0,0,0,0,0,-3,3,0,0,-2,-1,0,0, x 9,-9,9,-9,6,3,-3,-6,6,-6,-3,3,4,2,1,2, x -6,6,-6,6,-4,-2,2,4,-3,3,3,-3,-2,-1,-1,-2, x 2,-2,0,0,1,1,0,0,0,0,0,0,0,0,0,0, x 0,0,0,0,0,0,0,0,2,-2,0,0,1,1,0,0, x -6,6,-6,6,-3,-3,3,3,-4,4,2,-2,-2,-2,-1,-1, x 4,-4,4,-4,2,2,-2,-2,2,-2,-2,2,1,1,1,1/ do 42 m=1,my dx=xx(2)-xx(1) ff1(1,m)=(ff(2,m)-ff(1,m))/dx dx=xx(nx)-xx(nx-1) ff1(nx,m)=(ff(nx,m)-ff(nx-1,m))/dx do 41 n=2,nx-1 ff1(n,m)=polderiv(xx(n-1),xx(n),xx(n+1),ff(n-1,m),ff(n,m), xff(n+1,m)) 41 continue 42 continue do 44 n=1,nx dy=yy(2)-yy(1) ff2(n,1)=(ff(n,2)-ff(n,1))/dy dy=yy(my)-yy(my-1) ff2(n,my)=(ff(n,my)-ff(n,my-1))/dy do 43 m=2,my-1 ff2(n,m)=polderiv(yy(m-1),yy(m),yy(m+1),ff(n,m-1),ff(n,m), xff(n,m+1)) 43 continue 44 continue do 46 m=1,my dx=xx(2)-xx(1) ff12(1,m)=(ff2(2,m)-ff2(1,m))/dx dx=xx(nx)-xx(nx-1) ff12(nx,m)=(ff2(nx,m)-ff2(nx-1,m))/dx do 45 n=2,nx-1 ff12(n,m)=polderiv(xx(n-1),xx(n),xx(n+1),ff2(n-1,m),ff2(n,m), xff2(n+1,m)) 45 continue 46 continue do 53 n=1,nx-1 do 52 m=1,my-1 d1=xx(n+1)-xx(n) d2=yy(m+1)-yy(m) d1d2=d1*d2 yy0(1)=ff(n,m) yy0(2)=ff(n+1,m) yy0(3)=ff(n+1,m+1) yy0(4)=ff(n,m+1) yy1(1)=ff1(n,m) yy1(2)=ff1(n+1,m) yy1(3)=ff1(n+1,m+1) yy1(4)=ff1(n,m+1) yy2(1)=ff2(n,m) yy2(2)=ff2(n+1,m) yy2(3)=ff2(n+1,m+1) yy2(4)=ff2(n,m+1) yy12(1)=ff12(n,m) yy12(2)=ff12(n+1,m) yy12(3)=ff12(n+1,m+1) yy12(4)=ff12(n,m+1) do 47 k=1,4 z(k)=yy0(k) z(k+4)=yy1(k)*d1 z(k+8)=yy2(k)*d2 z(k+12)=yy12(k)*d1d2 47 continue do 49 l=1,16 xxd=0. do 48 k=1,16 xxd=xxd+iwt(k,l)*z(k) 48 continue cl(l)=xxd 49 continue l=0 do 51 k=1,4 do 50 j=1,4 l=l+1 cc(n,m,k,j)=cl(l) 50 continue 51 continue 52 continue 53 continue return end subroutine jeppe2(x,y,nx,my,xx,yy,cc,z) implicit real*8(a-h,o-z) dimension xx(nx),yy(my),cc(nx,my,4,4) n=locx(xx,nx,x) m=locx(yy,my,y) t=(x-xx(n))/(xx(n+1)-xx(n)) u=(y-yy(m))/(yy(m+1)-yy(m)) z=0. do 1 l=4,1,-1 z=t*z+((cc(n,m,l,4)*u+cc(n,m,l,3))*u . +cc(n,m,l,2))*u+cc(n,m,l,1) 1 continue return end integer function locx(xx,nx,x) implicit real*8(a-h,o-z) dimension xx(nx) if(x.le.xx(1)) then locx=1 return endif if(x.ge.xx(nx)) then locx=nx-1 return endif ju=nx+1 jl=0 1 if((ju-jl).le.1) go to 2 jm=(ju+jl)/2 if(x.ge.xx(jm)) then jl=jm else ju=jm endif go to 1 2 locx=jl return end real*8 function polderiv(x1,x2,x3,y1,y2,y3) implicit real*8(a-h,o-z) polderiv=(x3*x3*(y1-y2)-2.0*x2*(x3*(y1-y2)+x1* .(y2-y3))+x2*x2*(y1-y3)+x1*x1*(y2-y3))/((x1-x2)*(x1-x3)*(x2-x3)) return end