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Re: mg[14547] Multiplying Piecewise Continuous Functions.

• To: mathgroup at smc.vnet.net
• Subject: [mg14566] Re: mg[14547] Multiplying Piecewise Continuous Functions.
• From: Jack Goldberg <jackgold at math.lsa.umich.edu>
• Date: Fri, 30 Oct 1998 03:07:36 -0500
• Sender: owner-wri-mathgroup at wolfram.com

Sergio,

You asked in mg[14547] whether it is possible to multiply  two piecewise
continuous (PC) functions together (both written in Which form) so that
the answer is PC in the same form.  

Not only is the answer yes, but far more is possible and not difficult
to do, because I managed to do it.  

One can add, subtract, multiply, integrate (the integral being the 
unique continuous anti-derivative function modulo an arbitrary additive
constant).  The general term of Fourier Series expansion of such
functions is also easly found.

I have mentioned this in an earlier post but didn"t think there was 
enough interest in posting the code.  I have changed my mind and  will
post the code in the hopes that a good programmer will revise it so
that it is suitable for inclusion in MathSource.

In fact I was thinking of submitting an article on this very topic to 
one of the few journals devoted to Mathematica, but their publication 
frequency seems so erratic to me that I never got around to doing so.
When was the last Mathematica Journal published?

Jack Goldberg
Dept. of Math
University of Michigan
Ann Arbor MI, 48109