Updates:
Status: Valid
Labels: Assumptions Integration Evalf
Comment #1 on issue 4066 by [email protected]: integrate(abs(y - x**2),
(y,0,2)) raises ValueError: gamma function pole
http://code.google.com/p/sympy/issues/detail?id=4066
The full traceback is worth looking at
In [6]: In [3]: integrate(abs(y - x**2), (y,0,2))
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-6-a60159bcc795> in <module>()
----> 1 integrate(abs(y - x**2), (y,0,2))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/utilities/decorator.py
in
threaded_func(expr, *args, **kwargs)
33 func(expr.rhs, *args,
**kwargs))
34 else:
---> 35 return func(expr, *args, **kwargs)
36
37 return threaded_func
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/integrals.py
in
integrate(*args, **kwargs)
1281 if isinstance(integral, Integral):
1282 return integral.doit(deep=False, meijerg=meijerg,
conds=conds,
-> 1283 risch=risch, manual=manual)
1284 else:
1285 return integral
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/integrals.py
in
doit(self, **hints)
553 function, xab[0],
554 meijerg=meijerg1, risch=risch, manual=manual,
--> 555 conds=conds)
556 if antideriv is None and meijerg1 is True:
557 ret = try_meijerg(function, xab)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/integrals.py
in
_eval_integral(self, f, x, meijerg, risch, manual, conds)
931 # rewrite using G functions
932 try:
--> 933 h = meijerint_indefinite(g, x)
934 except NotImplementedError:
935 from sympy.integrals.meijerint import _debug
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/meijerint.py
in
meijerint_indefinite(f, x)
1595 results = []
1596 for a in list(_find_splitting_points(f, x)) + [S(0)]:
-> 1597 res = _meijerint_indefinite_1(f.subs(x, x + a), x)
1598 if res is None:
1599 continue
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/meijerint.py
in
_meijerint_indefinite_1(f, x)
1610 _debug('Trying to compute the indefinite integral of',
f, 'wrt', x)
1611
-> 1612 gs = _rewrite1(f, x)
1613 if gs is None:
1614 # Note: the code that calls us will do expand() and try
again
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/meijerint.py
in
_rewrite1(f, x, recursive)
1547 """
1548 fac, po, g = _split_mul(f, x)
-> 1549 g = _rewrite_single(g, x, recursive)
1550 if g:
1551 return fac, po, g[0], g[1]
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/cache.py in
wrapper(*args, **kw_args)
91 except (KeyError, TypeError):
92 pass
---> 93 r = func(*args, **kw_args)
94 try:
95 func_cache_it_cache[k] = r
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/meijerint.py
in
_rewrite_single(f, x, recursive)
1453 for fac, g in terms:
1454 r1 =
_get_coeff_exp(unpolarify(fac.subs(subs).subs(z, x),
-> 1455
exponents_only=True), x)
1456 g = g.subs(subs).subs(z, x)
1457 # NOTE these substitutions can in principle
introduce oo,
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/integrals/meijerint.py
in
_get_coeff_exp(expr, x)
306 """
307 from sympy import powsimp
--> 308 (c, m) = expand_power_base(powsimp(expr)).as_coeff_mul(x)
309 if not m:
310 return c, S(0)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/simplify/simplify.py
in powsimp(expr, deep, combine, force, measure)
2542
2543 if deep or expr.is_Add or expr.is_Mul and _y not in expr.args:
-> 2544 expr = expr.func(*[recurse(w) for w in expr.args])
2545
2546 if expr.is_Pow:
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/simplify/simplify.py
in <listcomp>(.0)
2542
2543 if deep or expr.is_Add or expr.is_Mul and _y not in expr.args:
-> 2544 expr = expr.func(*[recurse(w) for w in expr.args])
2545
2546 if expr.is_Pow:
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/simplify/simplify.py
in recurse(arg, **kwargs)
2533 _force = kwargs.get('force', force)
2534 _measure = kwargs.get('measure', measure)
-> 2535 return powsimp(arg, _deep, _combine, _force, _measure)
2536
2537 expr = sympify(expr)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/simplify/simplify.py
in powsimp(expr, deep, combine, force, measure)
2545
2546 if expr.is_Pow:
-> 2547 return recurse(expr*_y, deep=False)/_y
2548
2549 if not expr.is_Mul:
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/decorators.py in
__sympifyit_wrapper(a, b)
75 if not hasattr(b, '_op_priority'):
76 b = sympify(b, strict=True)
---> 77 return func(a, b)
78 except SympifyError:
79 return retval
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/decorators.py in
binary_op_wrapper(self, other)
116 else:
117 return f(self)
--> 118 return func(self, other)
119 return binary_op_wrapper
120 return priority_decorator
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/expr.py in
__mul__(self, other)
160 @call_highest_priority('__rmul__')
161 def __mul__(self, other):
--> 162 return Mul(self, other)
163
164 @_sympifyit('other', NotImplemented)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/cache.py in
wrapper(*args, **kw_args)
91 except (KeyError, TypeError):
92 pass
---> 93 r = func(*args, **kw_args)
94 try:
95 func_cache_it_cache[k] = r
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/operations.py in
__new__(cls, *args, **options)
38 return args[0]
39
---> 40 c_part, nc_part, order_symbols = cls.flatten(args)
41 is_commutative = not nc_part
42 obj = cls._from_args(c_part + nc_part, is_commutative)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/mul.py in
flatten(cls, seq)
178 a, b = b, a
179 assert not a is S.One
--> 180 if not a.is_zero and a.is_Rational:
181 r, b = b.as_coeff_Mul()
182 if b.is_Add:
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/assumptions.py
in getit(self)
142 if self._assumptions is self.default_assumptions:
143 self._assumptions = self.default_assumptions.copy()
--> 144 return _ask(fact, self)
145
146 getit.func_name = as_property(fact)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/assumptions.py
in _ask(fact, obj)
195 continue
196 if pk in handler_map:
--> 197 _ask(pk, obj)
198
199 # we might have found the value of fact
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/assumptions.py
in _ask(fact, obj)
185 pass
186 else:
--> 187 a = evaluate(obj)
188 if a is not None:
189 assumptions.deduce_all_facts(((fact, a),))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/power.py in
_eval_is_positive(self)
164
165 def _eval_is_positive(self):
--> 166 if self.base.is_positive:
167 if self.exp.is_real:
168 return True
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/assumptions.py
in getit(self)
142 if self._assumptions is self.default_assumptions:
143 self._assumptions = self.default_assumptions.copy()
--> 144 return _ask(fact, self)
145
146 getit.func_name = as_property(fact)
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/assumptions.py
in _ask(fact, obj)
185 pass
186 else:
--> 187 a = evaluate(obj)
188 if a is not None:
189 assumptions.deduce_all_facts(((fact, a),))
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/expr.py in
_eval_is_positive(self)
668 try:
669 # check to see that we can get a value
--> 670 n2 = self._eval_evalf(2)
671 if n2 is None:
672 raise AttributeError
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/core/function.py in
_eval_evalf(self, prec)
394 try:
395 mpmath.mp.prec = prec
--> 396 v = func(*args)
397 finally:
398 mpmath.mp.prec = orig
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/mpmath/ctx_mp_python.py
in
f(x, **kwargs)
991 if hasattr(x, '_mpf_'):
992 try:
--> 993 return ctx.make_mpf(mpf_f(x._mpf_, prec,
rounding))
994 except ComplexResult:
995 # Handle propagation to complex
/Users/aaronmeurer/Documents/Python/sympy/sympy/sympy/mpmath/libmp/gammazeta.py
in
mpf_gamma(x, prec, rnd, type)
1964 if type == 2:
1965 return fzero
-> 1966 raise ValueError("gamma function pole")
1967 # n = x
1968 n = man << exp
ValueError: gamma function pole
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