Numerical Analysis Programs Using Fortran 90 - University of ...

Problem: Write a program to find the interpolated value for x = 0. 7 ,
using divided difference formula, for these tabulated data.
X 0 0.5 1 1.4 2 3.2 5.5
F(x) -1.25 -3.5 6 2.32 1.5 1.27 5.6
program Divided_Differences_Iterpolation
dimension x(20),y(20),d(20,20)
n=7
xx=.7
data (x(i), i=1,7) /0,.5,1,1.4,2,3.2,5.5/
data (y(i), i=1,7)/-1.25,-3.5,6,2.32,1.5,1.27,5.6/
s=y(1)
do i=1,n-1
do j=1,n-i
y(j)=(y(j+1)-y(j))/(x(j+i)-x(j))
d(i,j)=y(j)
print*,d(i,j)
enddo
enddo
do i=1,n-1
p=1
do j=1,i
p=p*(xx-x(j))
enddo
s=s+d(i,1)*p
enddo
print*,'Interpolation of(',xx,')=',s
end
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Interpolation of (0.7) =2.290929
20