Comment #4 on issue 2625 by matt...@gmail.com: Imaginary unit in R,
ordering of complex numbers
http://code.google.com/p/sympy/issues/detail?id=2625
Just to note this: we use the following ordering when sorting expressions
(involving imaginary unit):
In [1]: sorted([2 + 3*I, 2 + I, I, -I, 3, -I + 1, 2*I, -1], key=lambda x:
sympify(x).sort_key())
Out[1]: [-1, 3, -ⅈ, ⅈ, 2⋅ⅈ, 1 - ⅈ, 2 + ⅈ, 2 + 3⋅ⅈ]
Reals come first (natural order), then complexes are ordered by (re(z),
im(z)). This ordering is used by (for example) by functions that return
roots of polynomials:
In [2]: roots((x - 1)*(x + 2)*x*(x - 1 + I)*(x - 1 - I)*(x + I), x,
multiple=True)
Out[2]: [-2, 0, 1, -ⅈ, 1 - ⅈ, 1 + ⅈ]
But that doesn't imply that < and > have to work on complexes.
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