Re: How to prevent from simplification?

*To*: mathgroup at smc.vnet.net*Subject*: [mg52469] Re: [mg52441] How to prevent from simplification?*From*: "David Park" <djmp at earthlink.net>*Date*: Sun, 28 Nov 2004 01:06:56 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Christian, There is a package, ExpressionManipulation.m, and an associated tutorial EvaluationTutorial.nb, at my web site below that may help with your problem. Ted Ersek helped me with this package. It has routines for selective manipulation and evaluation of expressions in held expressions. For your example we could do... Needs["Algebra`ExpressionManipulation`"] HoldForm[a + b/c] % /. {a -> 1, b -> 4, c -> 2} % // EvaluateAtPattern[_Times] % // EvaluateAtPattern[_Plus] giving in succession... a + b/c 1 + 4/2 1 + 2 3 Or with a different choice of values... HoldForm[a + b/c] % /. {a -> 1, b -> 2, c -> 3} % // EvaluateAtPattern[_Times, \[Infinity], N] % // EvaluateAtPattern[_Plus] a + b/c 1 + 2/3 1 + 0.66667 1.66667 In the third step an extended form of EvaluateAtPattern was used to convert 2/3 to an approximate number by applying the N function. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Christian Auner [mailto:mca at nurfuerspam.de] To: mathgroup at smc.vnet.net How can I substitute values into an expression and prevent it from beeing evaluated and simplified? Assume I have an expression like a + b/c and I want to substitute values for a,b and such that the result looks like number + number That is the evalution stops right before the addition. I already tried HoldForm but it didn't work.