# lagrange interpolation polynomial

• June 21st 2011, 10:40 PM
demode
lagrange interpolation polynomial
I have some difficulty understanding a step in the following solved problem on lagrange interpolating polynomials:

http://img846.imageshack.us/img846/3...olatingpol.png

So, in the 5th line of the working, how did they go from 1/2 to 4, and from 1/6 to 6? How did they change those?
• June 21st 2011, 10:46 PM
FernandoRevilla
Re: lagrange interpolation polynomial
Quote:

Originally Posted by demode
So, in the 5th line of the working, how did they go from 1/2 to 4, and from 1/6 to 6? How did they change those?

In $\mathbb{Z}_7$ we have $2\cdot 4=1$ so $1/2=4$ etc.