problem formulation in plot2d function



The first one should be 

y(x):= if x>=-1 and x<=1 then 4-x^2 else 2$


Rich
------------Original Message------------
From: "Ronald Modesitt" <rmodesi at msn.com>
To: maxima at math.utexas.edu
Date: Tue, May-6-2008 10:19 PM
Subject: problem formulation in plot2d function
Hi all,


My function is defined in Maxima as follows 
y(x):= if x>=-1 or x<=1 then 4-x^2 else 2$
and is plotted with
                plot2d(y(x),[x,-5,5], [y,-1,8])
however the plot is incorrect. It only plots the parabola (4-x^2), even outside the given range, and not the constant (2).
 
Redefining the function
                y(x):= if x<-1 or x>1 then 2 else 4-x^2$
with the same plot2d command as above yields the correct plot.
 
Can anyone see a problem with my first form?
 
Thanks
 
Ron
 
Ronald F. Modesitt, PE
 
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