Status: Accepted
Owner: asmeurer
Labels: Type-Defect Priority-Medium
New issue 2001 by asmeurer: log(1, 1) RuntimeError: maximum recursion depth
exceeded
http://code.google.com/p/sympy/issues/detail?id=2001
In [8]: log(1, 1)
---------------------------------------------------------------------------
RuntimeError Traceback (most recent call last)
/Users/aaronmeurer/Documents/python/sympy/sympy/<ipython console> in
<module>()
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/multidimensional.pyc
in
wrapper(*args, **kwargs)
133 result = apply_on_element(wrapper, args,
kwargs, n)
134 return result
--> 135 return f(*args, **kwargs)
136 wrapper.__doc__ = f.__doc__
137 wrapper.__name__ = f.__name__
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/cache.pyc in
wrapper(*args, **kw_args)
83 except KeyError:
84 pass
---> 85 func_cache_it_cache[k] = r = func(*args, **kw_args)
86 return r
87
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/function.pyc in
__new__(cls, *args, **options)
210 # UC: Function('f')(x)
211 # UC: sin(x)
--> 212 return Application.__new__(cls, *args, **options)
213
214
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/multidimensional.pyc
in
wrapper(*args, **kwargs)
133 result = apply_on_element(wrapper, args,
kwargs, n)
134 return result
--> 135 return f(*args, **kwargs)
136 wrapper.__doc__ = f.__doc__
137 wrapper.__name__ = f.__name__
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/cache.pyc in
wrapper(*args, **kw_args)
83 except KeyError:
84 pass
---> 85 func_cache_it_cache[k] = r = func(*args, **kw_args)
86 return r
87
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/core/function.pyc in
__new__(cls, *args, **options)
108 if options.get('evaluate') is False:
109 return super(Application, cls).__new__(cls, *args,
**options)
--> 110 evaluated = cls.eval(*args)
111 if evaluated is not None:
112 return evaluated
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/functions/elementary/exponential.pyc
in
eval(cls, arg, base)
278 base = int(base)
279 arg = int(arg)
--> 280 n = multiplicity(base, arg)
281 return S(n) + log(arg // base ** n) / log(base)
282 if base is not S.Exp1:
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/ntheory/factor_.pyc
in multiplicity(p, n)
68 n = nnew
69 continue
---> 70 return m + multiplicity(p, n)
71 n, rem = divmod(n, p)
72 return m
...
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/ntheory/factor_.pyc
in multiplicity(p, n)
68 n = nnew
69 continue
---> 70 return m + multiplicity(p, n)
71 n, rem = divmod(n, p)
72 return m
/Users/aaronmeurer/Documents/python/sympy/sympy/sympy/ntheory/factor_.pyc
in multiplicity(p, n)
68 n = nnew
69 continue
---> 70 return m + multiplicity(p, n)
71 n, rem = divmod(n, p)
72 return m
RuntimeError: maximum recursion depth exceeded
(I think) it should return nan. That's what similar things do:
In [9]: log(0, 1)
Out[9]: -∞
In [10]: log(1, 0)
Out[10]: 0
In [11]: log(0, 0)
Out[11]: nan
Or else, restrict the second argument to be positive and not equal to 1. I
haven't taken complex analysis yet though, so I don't know how these things
really play out with complex logarithms.
Here's what Maple does:
log[2](8);
3
log[1](1);
Error, (in log[1]) numeric exception: division by zero
log[0](0);
Error, (in ln) numeric exception: division by zero
log[1](0);
Error, (in ln) numeric exception: division by zero
log[0](1);
Error, (in ln) numeric exception: division by zero
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