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How to express a Product (special case) in Mathematica?

• To: mathgroup at smc.vnet.net
• Subject: [mg59094] How to express a Product (special case) in Mathematica?
• From: vdavidster at gmail.com
• Date: Thu, 28 Jul 2005 02:28:05 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

If you're familiar with the Lagrange interpolation polynomial, you'll
know that the coefficient term, phi, is defined as follows:

            n
phi_j (t) = TT     (t - t_i)
            i=0   -----------
            i!=j  (t_j - t_i)

Or in LaTeX notation:

\phi_j(t) = \prod^{n}_{\stackrel{i=0}{i \neq j}} \frac{(t - t_i)}{(t_j
- t_i)}

Or in graphical form:
http://mathworld.wolfram.com/LagrangeInterpolatingPolynomial.html

How do I do that in Mathematica?
How do I specify a product that skips a value in its iterator, i? (i.e.
i != j)

Thanks!

David

• Follow-Ups:
  • Re: How to express a Product (special case) in Mathematica?
    • From: Adriano Pascoletti <pascolet@dimi.uniud.it>
  • Re: How to express a Product (special case) in Mathematica?
    • From: yehuda ben-shimol <bsyehuda@gmail.com>
  • Re: How to express a Product (special case) in Mathematica?
    • From: Pratik Desai <pdesai1@umbc.edu>