Re: Pattern Syntax for Alternate Heads with Default Value

*To*: mathgroup at smc.vnet.net*Subject*: [mg125854] Re: Pattern Syntax for Alternate Heads with Default Value*From*: Adriano Pascoletti <adriano.pascoletti at uniud.it>*Date*: Thu, 5 Apr 2012 05:48:30 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201204040827.EAA29886@smc.vnet.net>

In[1]:= f[x : _Real | _Integer : 2.5] := x^2; In[2]:= f[3] Out[2]= 9 In[3]:= f[1.5] Out[3]= 2.25 In[4]:= f[] Out[4]= 6.25 Adriano Pascoletti 2012/4/4 Ben <benp84 at gmail.com> > 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 > >

**References**:**Pattern Syntax for Alternate Heads with Default Value***From:*Ben <benp84@gmail.com>