What is the difference equation of a Butterworth filter?

*To*: mathgroup at smc.vnet.net*Subject*: [mg27380] What is the difference equation of a Butterworth filter?*From*: Elias Kyriakides <elias_kyriakides at hotmail.com>*Date*: Thu, 22 Feb 2001 02:25:26 -0500 (EST)*Organization*: Arizona State University*Sender*: owner-wri-mathgroup at wolfram.com

Can anybody provide me with the difference equation of a Butterworth filter? e.g. something like y[n] = a1x[n] +a2x[n-1] etc Thanks, Elias