Re: Redirecting input
- To: mathgroup at smc.vnet.net
- Subject: [mg92380] Re: Redirecting input
- From: Szabolcs Horvat <szhorvat at gmail.com>
- Date: Tue, 30 Sep 2008 07:34:02 -0400 (EDT)
- Organization: University of Bergen
- References: <200809271047.GAA22530@smc.vnet.net> <gbqcqk$e6c$1@smc.vnet.net>
Thomas Dowling wrote:
> Or, slightly simpler,
>
>
> f[x_] := x + 1
>
>
> In[7]= f@{100, 23, 44}
>
> Out[7]= {101, 24, 45}
>
> (rather than f /@ {100, 23, 44})
>
> f@2, etc.
This is misleading advice. The correct way is of course to use Map,
i.e. f /@ {1,2,3}. Your specific example accidentally works because
Plus happens to have the attribute Listable, but you did not mention
this explicitly.
With the function f[x_] := If[x > 0, x, 0], f[{1,2,3}] (which is
equivalent to f @ {1,2,3}) would produce a different result from f /@
{1,2,3}.
- References:
- Redirecting input
- From: Ignacio Plazeta <Ignacio.Plazeta@speednet.es>
- Redirecting input