hello eveyone! sorry, my English is not very good

I writed Neville algorithm

I want to creat a table(or a matrix) Q with

example:

f:=X->2^X;

with value of X: -2,1,0,1,2

-2 1/4

-1 1/2

0 1

1 2

2 4

I want to approximate f at x=0.5 by Neville

then: for i:=2,...,n (that case is 5)

for j:=2,...i

Q[i,j]=(x-X[i-j])*Q[i,j-1]-(x-X[i])*Q[i-1,j-1])/(X[i]-X[i-j])

output(Q)

this is:

-2 1/4 0 0 0 0

-1 1/2 0.875 0 0 0

0 1 1.25 1.3475 0 0

1 2 1.5 1.4375 1.421875 0

2 4 1 1.375 1.40625 **1.412109375**

do you understand my mind? sorry, my English is not very good

Regards

sunflower