Updates:
Summary: Should we rename primitive()? (and Expr.primitive() should call
primitive())
Cc: matt...@gmail.com
Comment #9 on issue 2308 by asmeurer: Should we rename primitive()? (and
Expr.primitive() should call primitive())
http://code.google.com/p/sympy/issues/detail?id=2308
Well, "primitive" already has its present meaning in the polys.
It's kind of a problem term, I guess. In differential algebra, i.e., the
theory of the Risch Algorithm, a "primitive element" is (roughly) an
element whose derivative does not contain itself. For example, any
logarithm is primitive, since log(x).diff(x) == 1/x, which does not contain
log(x). atan(x) is also primitive, and so is any function that is defined
in terms of a nonelementary integral (like erf).
And there are dozens of other uses (like primitive element in the sense of
algebraic extensions). The New Oxford American Dictionary that comes with
Mac OS X has this definition, "• Mathematics (of an algebraic or geometric
expression) from which another is derived, or which is not itself derived
from another."
Maple calls this primpart()
(http://www.maplesoft.com/support/help/Maple/view.aspx?path=content). In
the literature, this is just denoted as pp(p). I couldn't find a
Mathematica function for it at
http://reference.wolfram.com/mathematica/guide/Mathematica.html. It used
to be called Poly.as_primitive() in the old polys.
By the way, we should change Expr.primitive() (or whatever we decide to
call it) to just be a shortcut to the primitive() function, which uses the
polys.
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