Comment #20 on issue 1985 by asmeurer: as_real_imag() gives wrong answer
when expanding quotient
http://code.google.com/p/sympy/issues/detail?id=1985
Well, that isn't true anymore. The way it is after my patch,
as_real_imag() performs complex expansion to obtain the real and imaginary
parts, and expand(comlex=True) and re() and im() just trivial call
as_real_imag().
i.e., expand(complex=True) is (now) just a nice wrapper around
re_part, im_part = expr.as_real_imag()
return re_part + I*im_part
re() and im() are mostly useful as dummy/unevaluated type functions, except
that they try to evaluate themselves by default (maybe they should really
be Re() and Im(), which would also fix issue 1727, btw). Also, if
as_real_imag() can't determine for sure, it falls back onto those (like in
comment 13).
The main point of my patch is that now all the heavy lifting is done in
as_real_imag() instead of _eval_expand_complex(), which is much better
because it keeps the real and imaginary parts separate.
But these things should be moved into their respective issues, or new
issues if they don't fit anywhere.
By the way, "complex" expansion refers to the the real+imag complex,
not "complicated".
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