05.05.2011 23:18, Tom Bachmann пишет:
Added on the wiki page:
## The aims of assumptions
### for end-user.
To simplify expressions:
# positive, even
>>> refine(Abs(x), Assume(x, Q.positive))
x
>>> refine(sqrt(x**2), Assume(x, Q.positive))
x
>>> refine((-1)**(x+y), Assume(x, Q.even))
(-1)**y
# algebraic fields
>>> refine(sqrt(x**2), Assume(x, Q.real))
Abs(x)
# mixed
>>> refine(exp(pi*I*2*(x+Rational(1,4))), Assume(x, Q.integer))
I
### for core
Use some logic and facts to implement calculation in convenient mode.
`.is_bounded`, `is_infinity`, `is_zero` and so on.
## Classification of assumptions
- related with symbols for simplification, e.g. `Q.positive`, `Q.even`.
- related with algebraic fields/rings, e.g. `Q.real`, `Q.complex`.
- related with some facts, e.g. `.is_bounded`, `is_infinity`, `is_zero`
and so on.
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