Re: A variable defaulting to a previous variable?

*To*: mathgroup at smc.vnet.net*Subject*: [mg121963] Re: A variable defaulting to a previous variable?*From*: Leonid Shifrin <lshifr at gmail.com>*Date*: Fri, 7 Oct 2011 04:49:02 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201110060825.EAA22765@smc.vnet.net>

Here is one way: ClearAll[f]; Module[{z}, f[x_, y_: z] := Block[{z = x}, x + y]; ] For more details and an explanation, see http://stackoverflow.com/questions/7394113/defining-a-function-with-an-optional-value-that-is-by-default-a-function-of-anoth/7394668#7394668 Regards, Leonid On Thu, Oct 6, 2011 at 12:25 PM, Brentt <brenttnewman at gmail.com> wrote: > How would one go about making a variable default to a previous variable? > > I would like results like this: > > In[1]= f[x_, y_: x] := x+y; > > In[2]= f[2,3] > > Out[1]= 5 > > In[3]= f[3] > > Out[1]= 6 > > > > > > But, of course, Mathematica won't let me use a previous argument for the > default of the next argument. Is there a way to do this? >

**References**:**A variable defaulting to a previous variable?***From:*Brentt <brenttnewman@gmail.com>