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Re: Function argument types

• To: mathgroup at smc.vnet.net
• Subject: [mg112953] Re: Function argument types
• From: Murray Eisenberg <murray at math.umass.edu>
• Date: Thu, 7 Oct 2010 03:37:58 -0400 (EDT)

One keyword would be PatternTest. A more general one would be "pattern".

Integer is not a function name, so that f[n_?Integer] := ... would never 
allow an integer argument to be accepted as such and thus allow f to be 
calculated using whatever followed the ":=".

On the other hand, Integer is a possible Head, as in

   Head[5]
Integer

so that f[n_Integer]:= ... would accept an integer as such and proceed 
with applying the definition.


On 10/6/2010 3:16 AM, Sam Takoy wrote:
> Hi,
>
> I can't see to find the answer to this basic question:
>
> What's the difference between
>
> f[n_?Integer]:=
>
> and
>
> f[n_Integer]:=
>
> I would be happy to read more about this, but what's the keyword?
>
> Thanks,
>
> Pavel
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
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