Re: search for an operator in an expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg78195] Re: search for an operator in an expression*From*: Szabolcs <szhorvat at gmail.com>*Date*: Mon, 25 Jun 2007 07:06:43 -0400 (EDT)*Organization*: University of Bergen*References*: <f5iuqu$a99$1@smc.vnet.net>

Daniel wrote: > Is there a way to search for an operator in a symbolic expression? My wish is to show that there is only "+" in a very large expression. Rather than showing an expression on multiple pages I would like to perform a search that shows there is only "+" between the terms. Converting to a string does not seem to work since the expression is written on multiple lines(fractions, exponents etc..) > > Thanks > If you have Mathematica <= 5.2, read the first few chapters from Principles of Mathematica in the Mathematica book to understand how expressions are represented (and how they can be manipulated). For Mathematica 6.0, http://reference.wolfram.com/mathematica/guide/Expressions.html is a good starting point. Use FullForm to see how expressions are represented. FreeQ[expr, Plus] tells you if there are any additions in the expression. I am sure that you want to do something more complicated than this, but I cannot answer your question unless you formulate it more precisely, and give some examples. If there are fractions in the expression, then clearly addition is not the only operation: there is also division, etc. Szabolcs