It's worse than that...
sage: t=((1/10)*I/pi)^(3/2)
sage: t
(1/10*I/pi)^(3/2)
sage: t^2
This doesn't return. An I had to insist to interrupt (had to strike C-C 6
times in emacs' sage-shell-mode...)
^C^C^C^C^C^C---------------------------------------------------------------------------
KeyboardInterrupt Traceback (most recent call last)
<ipython-input-31-f00da4fd424a> in <module>()
----> 1 t**Integer(2)
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/element.pyx
in sage.structure.element.Element.__pow__
(build/cythonized/sage/structure/element.c:14088)()
2038 return (<Element>left)._pow_(right)
2039 if BOTH_ARE_ELEMENT(cl):
-> 2040 return coercion_model.bin_op(left, right, pow)
2041
2042 cdef long value
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/coerce.pyx
in sage.structure.coerce.CoercionModel.bin_op
(build/cythonized/sage/structure/coerce.c:9800)()
1153 return (<Action>action)._act_(x, y)
1154 else:
-> 1155 return (<Action>action)._act_(y, x)
1156
1157 # Now coerce to a common parent and do the operation there
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/coerce_actions.pyx
in sage.structure.coerce_actions.IntegerPowAction._act_
(build/cythonized/sage/structure/coerce_actions.c:10173)()
861 integer_check_long(n, &value, &err)
862 if not err:
--> 863 return e._pow_long(value)
864 return e._pow_int(n)
865
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/element.pyx
in sage.structure.element.Element._pow_long
(build/cythonized/sage/structure/element.c:14635)()
2115 Generic path for powering with a C long.
2116 """
-> 2117 return self._pow_int(n)
2118
2119
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/expression.pyx
in sage.symbolic.expression.Expression._pow_int
(build/cythonized/sage/symbolic/expression.cpp:25386)()
4049 pi^4
4050 """
-> 4051 return self._pow_(self._parent(other))
4052
4053 def derivative(self, *args):
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/expression.pyx
in sage.symbolic.expression.Expression._pow_
(build/cythonized/sage/symbolic/expression.cpp:25211)()
4033 relational_operator(self._gobj))
4034 else:
-> 4035 x = g_pow(self._gobj, nexp._gobj)
4036 return new_Expression_from_GEx(self._parent, x)
4037
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/rings/number_field/number_field_element.pyx
in sage.rings.number_field.number_field_element.NumberFieldElement.__pow__
(build/cythonized/sage/rings/number_field/number_field_element.cpp:22076)()
2316 if (isinstance(base, NumberFieldElement) and
2317 (isinstance(exp, Integer) or type(exp) is int or exp in
ZZ)):
-> 2318 return generic_power(base, exp)
2319
2320 if (isinstance(base, NumberFieldElement) and exp in QQ):
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/arith/power.pyx
in sage.arith.power.generic_power
(build/cythonized/sage/arith/power.c:2376)()
81 raise NotImplementedError("non-integral exponents not
supported")
82 if not err:
---> 83 return generic_power_long(a, value)
84
85 if n < 0:
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/arith/power.pyx
in sage.arith.power.generic_power_long
(build/cythonized/sage/arith/power.c:2663)()
100 u = -u
101 a = invert(a)
--> 102 return generic_power_pos(a, u)
103
104
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/arith/power.pyx
in sage.arith.power.generic_power_pos
(build/cythonized/sage/arith/power.c:2796)()
118 n >>= 1
119 while n:
--> 120 sig_check()
121 apow *= apow
122 if n & 1:
KeyboardInterrupt:
sage:
This, IMNSHO, is a (quite serious) bug, affecting a very basic
functionality of Sage.
That's why I have opened Trac#28620
<https://trac.sagemath.org/ticket/28620#ticket> against "symbolics", and
flagged it as "critical"
HTH,
Le mardi 15 octobre 2019 17:17:41 UTC+2, Dima Pasechnik a écrit :
>
> On Tue, Oct 15, 2019 at 3:57 PM 'Florian Hanisch' via sage-devel
> <sage-...@googlegroups.com <javascript:>> wrote:
> >
> > Hi,
> >
> > this might be a duplicate (sorry) but I could not find this issue
> described anywhere else. I have been running the code
> >
> > k=1.0
> > (I*k/(2*pi*5))^(6/2)
> >
> > and got the result
> >
> > (1.00000046096651e-4294967297*I)/pi^3
> >
> > This is clearly way too small, adding CC(...) to get a numerical value
> does not resolve
> > the problem. However, simply replacing 6/2 by 3 yields the correct
> result:
> >
> > (I*k/(2*pi*5))^(3)
> > result: -0.00100000000000000*I/pi^3
> >
> > Did I make some stupid and obvious error or is this just a strange bug ?
> I am using
> > sage 8.6 (jupyter notebook) on a linux computer (Centos 7, 64 bit). I
> tried these code
> > snippets on cocalc and ran into the same problems. Friends of mine have
> also reported the
> > problem on sage 8.8.
>
> yes, it appears to be a bug. here is a slightly easier example:
>
> sage: t
> (0.100000000000000*I/pi)^(3/2)
> sage: t.n()^2
> -6.77626357803440e-21 - 0.0000322515344331995*I
> sage: t.n()
> # a correct numerical value
> -0.00401569012955429 + 0.00401569012955429*I
> sage: t^2
> # pynac bug ?
> (1.00000046096651e-4294967297*I)/pi^3
>
> maxima is doing it right:
>
> sage: maxima(t)
> ((0.1*%i)/%pi)^(3/2)
> sage: maxima(t)^2
> -(0.001*%i)/%pi^3
>
>
>
>
> >
> > Thanks a lot,
> >
> > Florian
> >
> >
> >
> > --
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> https://groups.google.com/d/msgid/sage-devel/ba2015a4-6249-4d4b-98ce-5d8e115fd95a%40googlegroups.com.
>
>
>
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