RE: Re: Function as an argument of the function

*To*: mathgroup at smc.vnet.net*Subject*: [mg34697] RE: [mg34677] Re: Function as an argument of the function*From*: "DrBob" <majort at cox-internet.com>*Date*: Sat, 1 Jun 2002 04:29:04 -0400 (EDT)*Reply-to*: <drbob at bigfoot.com>*Sender*: owner-wri-mathgroup at wolfram.com

That code doesn't even execute: OneArgFunctionQ[_] := False; OneArgFunctionQ[Function[expr_]] := FreeQ[expr, Slot[n_ /; n > 1]] && FreeQ[expr, _SlotSequence]; OneArgFunctionQ[Function[vars_, expr_]] := Length[vars] == 1; Function::flpar: Parameter specification vars_ in Function[vars_,expr_] \ should be a symbol or a list of symbols. If you decide to check DownValues, don't forget to check SubValues as well. However, built-in functions will defeat that method and perhaps ANY method. Bobby Treat -----Original Message----- From: Orestis Vantzos [mailto:atelesforos at hotmail.com] To: mathgroup at smc.vnet.net Subject: [mg34697] [mg34677] Re: Function as an argument of the function maltomek at hotmail.com (Tomek) wrote in message news:<ad4jg1$jm2$1 at smc.vnet.net>... > Hi. > I have to write a short function in Mathematica. But I have one > problem with it. One of arguments of my function have to be a > function of one variable. > How can I check if the argument of the function is a function of one > variable (I wish there's FunctionQ)? Well, if you limit your choice down to pure functions, you can use the following code to check whether the pure function accepts a single argument: OneArgFunctionQ[_] := False; OneArgFunctionQ[Function[expr_]] := FreeQ[expr, Slot[n_ /; n > 1]] && FreeQ[expr, _SlotSequence]; OneArgFunctionQ[Function[vars_, expr_]] := Length[vars] == 1; Examples: OneArgFunctionQ[#&] --> True OneArgFunctionQ[#+#2&] --> False OneArgFunctionQ[Function[{x},x^2]] --> True OneArgFunctionQ[Function[{x,y},x+y]] --> False If you want to check symbols like Sin, Cos, etc. things get ugly really fast. You could theoreticaly check the DownValues of the symbol, but I wouldn't bother unless it was absolutely imperative. Orestis