Re: multiple outputs from a function
- To: mathgroup at smc.vnet.net
- Subject: [mg52771] Re: multiple outputs from a function
- From: "Dr. Wolfgang Hintze" <weh at snafu.de>
- Date: Mon, 13 Dec 2004 04:22:12 -0500 (EST)
- References: <cpekeh$744$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Ben,
just put the output in a list.
Here's an example which gives the first three powers of a variale x
Definition
In[9]:=
pow[x_] := {x, x^2, x^3}
Execution
In[10]:=
y = pow[8]
Result
Out[10]=
{8, 64, 512}
The specific components of the list can then be extracted one by one
using Part, or [[]]. Example: the second value is
In[13]:=
y[[2]]
Out[13]=
64
Hope this helps,
Wolfgang
Ben Barrowes wrote:
> I feel I must be missing something fundamental...
>
> How do you write a function (or ?) in Mathematica which produces more
> than one output?
>
> Let's say I have some data and I want a single function to calculate the
> mean, variance, std, etc, more than one thing and return those? I know
> that there are builtin functions for those parameters, but the point is
> I want to define functions with more than one output.
>
> The only examples I can find are along the lines of:
>
> f[x_,y_]:=x^2+y^2;
>
> which have only a single result.
>
> Is there a different structure altogether, such as a Subroutine, which
> allows multiple results from a single subunit?
>
> One thought I had was that because Mathematica treats everything as
> global unless defined specifically local (e.g. in a module), that
> variables used in a procedure would be accessible and would thus be a
> "result", but it seems scoping problems would arise if this was used too
> often. For example:
>
> In[67]:=
> t1[x_,y_]:=(a1=x^2+y;a2=x+y^2;x+y)
>
> In[68]:=
> t2=t1[5,6]
>
> Out[68]=
> 11
>
> In[69]:=
> a1
>
> Out[69]=
> 31
>
> In[70]:=
> a2
>
> Out[70]=
> 41
>
> Is this the accepted method for extracting multiple results from one
> function definition?
>
>
> Ben Barrowes
>
>