Terrence Cole wrote:
Can someone explain to me what python is doing here?
Python 3.1.1 (r311:74480, Feb 3 2010, 13:36:47)
[GCC 4.3.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
-0.1 ** 0.1
-0.7943282347242815
a = -0.1; b = 0.1
a ** b
(0.7554510437117542+0.2454609236416552j)
-abs(a ** b)
-0.7943282347242815
Why does the literal version return the signed magnitude and the
variable version return a complex?
I think this recently showed up on the list and the answer
involved the order of operations and precedence of "-" vs. "**".
To check, try
>>> (-0.1) ** 0.1
>>> -(0.1 ** 0.1)
The first one is what the assignment-to-variables gains you, but
I think "**" has a higher precedence than the unary-"-" so it
gets performed first.
I don't have Py3 on my machine here, and 2.5 rejects the first form:
Python 2.5.4 (r254:67916, Nov 19 2009, 19:46:21) [GCC 4.3.4] on
linux2
Type "help", "copyright", "credits" or "license" for more
information.
>>> -(0.1**0.1)
-0.79432823472428149
>>> (-0.1)**0.1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: negative number cannot be raised to a fractional power
But perhaps Py3 changes evaluation, returning an complex number.
-tkc
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