[求助] fortran程序能运行，生成结果是空的？

program main
  integer ist,dd 
  parameter(ist=50,dd=12) 
        dimension cor(ist)
        character*8 istid(ist)
  real istr(ist),istr19(ist,dd)
!    ---------------读实况值 istr(i)
    open(20,file='F:\shuju\sk_06R.txt')
       do  i=1,ist
       read(20,*)            
       enddo
    close(20)
!    ---------------读预报值 istr19(i,j)
    open(20,file='F:\shuju\ms_06R_26.txt')
         do  i=1,50
         read(20,*)(istr19(i,j),j=1,dd)
         enddo
    close(20)
open(2,file='F:\shuju\result\ACC_06R.txt')  !!!!输出ACC文件
     do j=1,ist
        write(2,'(I5,2x,<6>(f10.3,2X))')cor(j)
     enddo
   close(2)
   end

    Subroutine cor(x,y,n,coefficient)
        dimension x(n),y(n)
        real coefficient,avex,avey,sum1,sum2
        sum1=0.0;sum2=0.0
        do i=1,n
        sum1=x(i)+sum1
        sum2=y(i)+sum2
        enddo
        avex=sum1/n;avey=sum2/n
        sum1=0.0;sum2=0.0;sum3=0.0
        do j=1,n
        sum1=sum1+(x(j)-avex)*(y(j)-avey)
        sum2=sum2+(x(j)-avex)**2
        sum3=sum3+(y(j)-avey)**2
        enddo
        coefficient=sum1/sqrt(sum2*sum3)
        return
        end