Re: Not accepting function as parameter

*To*: mathgroup at smc.vnet.net*Subject*: [mg71774] Re: Not accepting function as parameter*From*: "Andrew Moylan" <andrew.j.moylan at gmail.com>*Date*: Wed, 29 Nov 2006 02:56:03 -0500 (EST)*References*: <ekbmj4$f87$1@smc.vnet.net>

As other posters have pointed out, not all (or even most) functions have head Function. Some have head Symbol. Really, in Mathematica, anything might be a function. In this example, the head is Derivative[1]: happy[Derivative[1][g], 1, 21]. In general, I think you just have to introduce your function happy as happy[f_, a_Integer, b_Integer], with no restriction on the first argument. To get really wild: one could conceive of a pattern that tests (by inspecting DownValues[f], SubValues, etc.) whether the argument f will behave as a suitable function. But such a test would also have to be too restrictive, since in not possible (even in principle---Godel's theorem and all that), given the definition of a function, to determine whether it's going to always return e.g. a number. On Nov 26, 8:25 pm, "wooks" <woo... at hotmail.com> wrote: > This is a piece of experimental code. The function happy does not > evaluate whenever I pass f as a parameter as in the example below. > > Clear[happy] > happy[ f_Function, a_Integer, b_Integer] := Module[{width = (b - > a)/1000}, > f[width]]; > > happy[ Sin, 1, 21] > > I'd be grateful for help.