Optional Alternatives
- To: mathgroup at smc.vnet.net
- Subject: [mg50010] Optional Alternatives
- From: Selwyn Hollis <sh2.7183 at misspelled.erthlink.net>
- Date: Wed, 11 Aug 2004 05:53:08 -0400 (EDT)
- References: <200408101002.GAA19525@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Is it possible to require a function argument to match alternative
patterns and be optional at the same time? As a toy example, suppose I
define
f[x:_Real|_Rational]:= x
Is there a way make the argument optional with a given default value,
say 0? I've tried this:
f[Optional[x:_Real|_Rational, 0]]:= x
and various other combinations with no success. (Of course I could do
this: f[]:= 0, but I'm interested in the more general issue.)
-----
Selwyn Hollis
http://www.appliedsymbols.com
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