How to Read This Function

*To*: mathgroup at smc.vnet.net*Subject*: [mg45671] How to Read This Function*From*: "Bruce W. Colletti" <bcolletti at compuserve.com>*Date*: Sat, 17 Jan 2004 02:34:40 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Re Mathematica 5.0. HelpBrowser/BuiltIn/AlgebraicComputation/FormulaManipulation/Assuming has an example that uses ff[a_?(Refine[# > 0] &)x_] := a*ff[x] Thus, ff[2x] returns 2 ff[x] ("If $Assumptions has no effect on ff...then ff pulls out positive numeric factors." What's the right way to interpret the function's lefthand side? My take is "Split the passed argument (#) into variables a and x, where a is the product of all positive numeric factors and x is the product of what remains." If this is correct, then I don't know for sure how the lefthand side says this. Must the argument be a product? If so, then how is the lefthand side saying this? Thanks. Bruce