The objective is to implement a Piecewise expression that gives 0 when n is
even, and 1 when n is odd. One way to do it is using the floor function
like below:
from sympy import *
from sympy.abc import n
f = Lambda((n,), Piecewise((0, Eq(n, floor(n / S(2)))),
(1, Eq(n, floor(n / S(2))+1))))
print(f(0))
print(f(1))
print(f(2))
print(f(3))
However, this returns the wrong output:
0
1
1
Piecewise()
The correct output should be:
0
1
0
1
Another way to achieve the same is to use:
from sympy import *
from sympy.abc import n
f = Lambda((n,), Piecewise((0, Eq((-1)**n, 1)),
(1, Eq((-1)**n, -1))))
print(f(0))
print(f(1))
print(f(2))
print(f(3))
and this returns the correct output. Is there a way to achieve this using
the floor function in the original code?
PS: Question also posted on
http://stackoverflow.com/questions/33289928/sympy-piecewise-expression-for-even-and-odd-numbers
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