Date: Feb 3, 2011 5:29 AM
Author: Charles Gillingham
Subject: Re: Mystifying Scoping of Piecewise Variable?

You want:

myFunc = Function[{x}, Piecewise[{{x^2, x < 0}, {x, x >= 0}}]];

Begin forwarded message:

From: Frank Iannarilli <frankeye@cox.net>
Date: February 02, 2011 3:08:08 AM
Subject: Mystifying Scoping of Piecewise Variable?

Perhaps I'm tired, but this is weird:

Clear[myFunc]

myFunc[y_] = Piecewise[{{x^2, x < 0}, {x, x >= 0}}]
(Same behavior below for either Set(=) or SetDelayed(:=) )

Plot[myFunc[y], {y, -10, 10}]
(returns empty plot)

Plot[myFunc[x], {x, -10, 10}]
(returns "expected" piecewise function plot)

What is the scoping of the Piecewise variable, in this case "x"?

How can one write a Module that creates and returns a Piecewise function? The scope of its argument is unclear to me.

Thanks