Re: Pattern Syntax for Alternate Heads with Default Value

*To*: mathgroup at smc.vnet.net*Subject*: [mg125874] Re: Pattern Syntax for Alternate Heads with Default Value*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Thu, 5 Apr 2012 05:55:29 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

On 4/4/12 at 4:27 AM, benp84 at gmail.com (Ben) wrote: >I'm trying to build a unary function which accepts only arguments >with two possible heads and has a default value. That is, something >like the following, except that this doesn't work. Anyone know how >to do this correctly? >f[(x_Real | x_Integer) : 2.5] := x^2; where f[3] = 9 and f[1.5] = >2.25 and f[] = 6.25 In[16]:= f[x_?(# \[Element] Reals &)] := x^2 f[x_] := 6.25 In[19]:= Clear[y]; f[y] Out[19]= 6.25 In[20]:= f[.8] Out[20]= 0.64 No need to test for integers since reals include integers.