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Re: Trying to recursively define a double factorial

• To: mathgroup at smc.vnet.net
• Subject: [mg126533] Re: Trying to recursively define a double factorial
• From: Tomas Garza <tgarza10 at msn.com>
• Date: Thu, 17 May 2012 04:11:35 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201205160820.EAA23026@smc.vnet.net>

I can't see where the "double" comes in. It seems to be an ordinary factorial and a Table of values for the factorial. E.g.
In[15]:= Clear[MyF1, n]; MyF1[n_Integer] := n*MyF1[n - 1] /; n > 1; MyF1[1]=  1;
In[16]:= Table[MyF1[k], {k, 3, 6}]

Out[16]= {6, 24, 120, 720}
-Tomas

> Date: Wed, 16 May 2012 04:20:52 -0400
> From: monsterbone at msn.com
> Subject: Trying to recursively define a double factorial
> To: mathgroup at smc.vnet.net
>
> My goal here is to define a recursive function for a double factorial.  T=
he domain of this function is the set of positive integers.  For a positive=
 even integer  n  the value DF[n] is the product of all positive even integ=
ers which are  <n.  For a positive odd integer   n   the value DF[n] is the=
 product of all positive odd integers which are <n. 
>
> I wanna make a recursive function of this double factorial without If(and=
 other similar statements). Here is my work so far:
>
>
> Clear[MyF1, n];
> MyF1[1] = 1;
> MyF1[n_Integer] /; (n > 0) := MyF1[n] = n*MyF1[n - 1]
>
> Table[MyF1[k], {k, (*integer*), (*integer*)}]
>
>
>
>                How do I do this?
>

• References:
  • Trying to recursively define a double factorial
    • From: Jorge Cantu <monsterbone@msn.com>