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Re: Question re I->-I
Taking a negative (which operates on the whole number) is NOT the same as taking a conjugate (which modifies only one part.) In this respect Rational numbers behave the same as Complex numbers. Do you expect a rule that only works on the denominator of a Rational to work for all expressions? 3/2 /. (1/2 -> 1/4) % // FullForm 3/2 Rational[3, 2] But this works: 3/2 /. Rational[a_, b_] -> Rational[a, 2 b] 3/4 Mathematica must have a module that handles the processing of ALL NUMBERS and it's a little futile to pull on one thread and ignore how this might affect everything else. The present system is not inconsistent, or illogical, or difficult to learn. Just learn it. David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: AES [mailto:siegman at stanford.edu] Alternative question: * Type in a rational polynomial in a simple variable "s" (format it any way you like), and apply this sRule. Is there any way you can reformat this rational polynomial, without changing its meaning, so as to get different results when the sRule is applied?