program plotfun
implicit none
integer:: i,n
real:: x,x0,x1,dx,yf1,yf2,f1,f2

read(5,*)x0,x1,n
dx=(x1-x0)/(n-1)
do i=1,n
   x=x0+(i-1)*dx
   yf1=f1(x,2.0,1.0,0.1,0.2)
   yf2=f2(x)
   write(6,100)x,yf1,yf2
100 format(3(x,f8.4))
enddo

end program plotfun

real function f1(xarg,a,b,c,d) 
implicit none
real,intent(in) ::xarg,a,b,c,d

real ::p1,p2,p3,xp1

f1=a+b*xarg+c*xarg**2+d*xarg**3

end function f1

real function f2(xarg) 
implicit none
real ::xarg

f2=xarg
end function f2