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Complex Algebra


To ken yip <yip-ken at CS.YALE.EDU>, and others who've discussed
about complex algebra:

For some months ago, I wrote a package Declare.m that allows
you to "declare" symbols to be real, integer, odd, even etc.
The package makes Mathematica simplify things nicely, for
example if you Declare[n,Integer] and Declare[{x,y},Real],
then EvenQ[2n] gives True, Sqrt[-x^2] gives I Abs[x]. Complex
algebra is simplified, too: Re[Exp[(x+I y)^2]] gives
E^(x^2-y^2)Cos[2x y]. (You has to load the standard package
Algebra/ReIm.m before this works.) The package, together with
test files, is available on the mathgroup anonymous ftp server
(128.174.20.50) in Symbolic/Mathematica/Packages/JANHUNEN.

I use the package frequently but not always, since it can
sometimes make Mathematica run very slowly.

Pekka Janhunen
Finnish Meteorological Institute, Geophysics Dept.
email: pjanhune at finsun.csc.fi



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