Re: Options in user-defined functions...

*To*: mathgroup at smc.vnet.net*Subject*: [mg60375] Re: Options in user-defined functions...*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Wed, 14 Sep 2005 03:27:51 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 9/13/05 at 6:07 AM, danwolf80_no_spam_ at libero.it (Daniele Lupo) wrote: >I've a little problem with a function. I've defined it in this way: >fun[x_,op1_:1,op2_:2,op3_:3]:= >Module[{....},f1[x,op1],f2[x,op2],f3[x,op3]] >So, when I use it, ops have their default values. >It works, but I'd like to use option; this why, if I want to change >only op3, I must to write every argument when I call the function, >while I'd like to write something like this: >fun[x,op3->4] >how can I do it? Basically, you need to rewrite your function along the lines of: SetOptions[fun, op1->1, op2->2, op3->3]; fun[x_, opts___]:= Module[{....}, f1[x,op1]/.{opts,Options[fun]}; f2[x,op2]/.{opts,Options[fun]}; f3[x,op3]/.{opts,Options[fun]}] A couple of additional thoughts. The package Utilities`FilterOPtions` is quite handy when creating functions with options. It allows you to call other functions which have options, ensuring each function gets only those options applicable to it. Roman Maeder presents a very clear discussion of options versus default values in chapter 3 of his book Programming in Mathematica. -- To reply via email subtract one hundred and four