program Interpolation
implicit none
real,dimension(4):: x,y
integer:: n ,i, j
real:: xp ,sum, p

data x /3.2, 2.7, 1.0, 4.8/
data y /2.0, 17.8, 14.2, 38.3/

n=4
xp=3.5
do i=1,n
   p=1
    do j=1,n
        if (i.eq.j) cycle
            p= p * ((xp-x(j)) / (x(i)-x(j)))
    enddo
        sum=sum+p*y(i)
enddo

write(*,1)"value of f(x) for point",xp,"=",sum
1 format(2x,a,f5.3,a,1x,f10.5)
end