Hi
I'm looking at Lucas Lehmer sequences. I am modelling them in Sympy.
I've created a function class:
class L(Function):
nargs = (1)
_recursions_maximum = S.Infinity
_recursions_count = 0
@classmethod
def set_recursion_count(cls, c):
cls._recursions_maximum = c
cls._recursions_count = 0
@classmethod
def eval(cls, x):
cls._recursions_count += 1
if cls._recursions_count > cls._recursions_maximum:
cls._recursions_maximum = S.Infinity
return
elif x is S.Zero:
return 4
else:
return (L(x-1)**2)-2
This does work mostly as expected although I am running into trouble with
the sympy cache:
n = Symbol('n', integer=True, positive=True)
L.set_recursion_count(2)
print(L(n))
>> (L(n - 2)**2 - 2)**2 - 2
print(L(4))
>> 1416317954
clear_cache()
L.set_recursion_count(2)
print(L(4))
>> (L(2)**2 - 2)**2 - 2
The first two outputs (highlighted with >>) are expected but the fourth
must be cached from somewhere?
Is there a better way to do this? Ideally, I'd like to avoid adding the
maximum recursion limit as an argument to my function.
Thanks in advance!
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sympy.
To view this discussion on the web visit
https://groups.google.com/d/msgid/sympy/be100c36-b81f-4a44-8669-a9f811547400%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
