Transformation of Expressions

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Transformation of Expressions*From*: rickli at aut.ee.ethz.ch (Martin Rickli)*Date*: Tue, 28 Jun 1994 17:28:03 +0200

My professor asked me the following: If we have an expression built with rational numbers and a irrational number, it is nown that there exists a ("linear") representation of the form f[irrational] = rational + rational*irrational e.g. Sqrt[ (3 + Sqrt[5])/2 ] = 1/2 + 1/2 Sqrt[5] (here Sqrt[5] is the irrational number). How can we find these rational numbers (of course using Mma)? To my regret I couldn't help him. Is it possible to set up transformation rules doing this (hopefully yes)? Thanks for any hint. With kind regards ______________________________________________________________________ Martin Rickli E-mail: Rickli at aut.ee.ethz.ch Automatic Control Laboratory ETH Zurich Physikstr. 3, ETL K12 CH-8092 Zurich, Switzerland