Am 24.03.2015 um 12:28 schrieb Paul Royik:
Maybe this is property of Python, but I'm not aware about it.
expr = 1/(2*sin(x/2 + pi/4)*cos(x/2 + pi/4))
equation = Eq(expr,expr)
equation == True # outputs True
equation is True # outputs False
Why True equation is not True?
In Python, "==" is value equality while "is" is object identity.
The differences are relevant in two ways:
1) "==" may change if you modify an object, "is" never does. This is
less relevant for SymPy because SymPy objects usually are not modified.
2) "is" cannot be redefined, "==" can. SymPy's S.true has its "=="
redefined so that it compares equal with "==".
Moreover, in IDE in which I'm working, when I write equation != True, it
tells me "this inspection detects equality comparison with a boolean
literal".
It's telling you that writing
xxx == True
is silly because you can simply write
xxx
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