Pattern Matching
- To: mathgroup at smc.vnet.net
- Subject: [mg49003] Pattern Matching
- From: "Bruce W. Colletti" <bcolletti at compuserve.com>
- Date: Mon, 28 Jun 2004 04:13:47 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
This command (built from recent traffic) extracts the quadratic's
coefficients and exponents:
Cases[4x + x^2, c_.*x^n_. -> {c,n}]
{{4,1}, {1,2}}
As I understand it, the symbol "_." uses the global default value for
the given variable, a value that can be set using Default.
Question: For the specific (illustrative) problem above, how would I
set (using Default[ ]) different default values for c and n? Or must I
do something like:
Cases[4x + x^2, (c_:5)*x^(n_:7) -> {c,n}]
Thanks.
Bruce
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