PRp v.1.1
Positive Real property test v.1.1

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12/17/1999
By Daniele Martini 
Send your comments or bug reports to:
hrhmart@tin.it
Other files by the same author:
S2S symbolic two ports solver
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PRp test v.1.0 is a little program written for ti-89 users who
attend advanced courses in electric circuits and have to deal
with positive real functions. Its purpose is to test the positive
real property of rational functions. This program makes use of the
Talbot criterion to evaluate functions. It has been tested with 
more than 30 exercises taken from an electric networks' theory
book. 
Two bugs of the previous version have been fixed. The utility has
been re-tested. A new version is expected by the end of January
2000 but hopefully this time it will not be for fixing bugs.
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Syntax:
 
prp(expr,var)
where expr is the function to be tested and var is the independent
variable.
Example:
prp((2s+1)/(2s^2+1),s)
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IMPORTANT!

PRp test gives correct answers when algebraic constants are not
involved. 

EXAMPLE:

3*s/(s^2+1) 
can be successfully tested

k*s/(s^2+1)
when you enter this function the program will say it is not a 
positive real function. Even if you specified K > 0. This is a
wrong answer. SO DO NOT USE PRp TO DEAL WITH PARAMETRIC FUNCTIONS.
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