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Re: piecewise vs which


The answer you seek is in the documentation for Piecewise. All
Piecewise functions have a default value of zero on their undefined
intervals. You can change this.

On 9/2/05, Bradley Stoll <BradleyS at harker.org> wrote:
> Consider defining a function in Mathematica (v. 5.2) in two different
> ways:  f[x_]=Piecewise[{{x^2,x<2},{3x,x>2}}] and
> g[x_]=Which[x<2,x^2,x>2,3x].  Notice that 2 is not in the domain of
> either function.  However, if I ask for f[2], Mathematica returns 0 and if I ask
> for g[2] Mathematica (correctly) returns nothing.  Is this a bug with
> Mathematica (that Mathematica returns 0 for f[2]), since 2 is not in the domain?
> While I have eyes, there is another question regarding limits.  Is it
> the case that Limit[f[x],x->2] defaulted as
> Limit[f[x],x->2,Direction->-1] (a right hand limit)?  Both return 6 in
> the above example.  I'm using Mathematica in my calculus class and would
> like to explain why Mathematica does certain things.  It doesn't seem
> that it would've been too difficult to just have two subroutines (a
> right and left hand limit) to determine whether a 'full' limit actually
> existed.
> Thanks!
> 
> Bradley
> 
> 


-- 
Chris Chiasson
http://chrischiasson.com/
1 (810) 265-3161


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