#4748: pass to quotient ring for exp
------------------------------+---------------------------------------------
Reporter: robertwb | Owner: somebody
Type: defect | Status: new
Priority: minor | Milestone: sage-4.1.1
Component: basic arithmetic | Keywords:
Reviewer: | Author:
Merged: |
------------------------------+---------------------------------------------
Description changed by robertwb:
Old description:
> This works
> {{{
> sage: sqrt(1+x+O(x^5))
> 1 + 1/2*x - 1/8*x^2 + 1/16*x^3 - 5/128*x^4 + O(x^5)
> }}}
>
> One would expect this to work:
>
> {{{
> sage: R.<x> = ZZ[[]]
> sage: exp(x+O(x^5))
> Traceback (most recent call last):
> File "<ipython console>", line 1, in <module>
> File "/Users/robert/sage/current/local/lib/python2.5/site-
> packages/sage/calculus/calculus.py", line 8415, in __call__
> return x.exp()
> File "power_series_ring_element.pyx", line 1383, in
> sage.rings.power_series_ring_element.PowerSeries.exp
> (sage/rings/power_series_ring_element.c:9850)
> File "power_series_ring_element.pyx", line 1305, in
> sage.rings.power_series_ring_element.PowerSeries.solve_linear_de
> (sage/rings/power_series_ring_element.c:9707)
> File "power_series_ring_element.pyx", line 1648, in
> sage.rings.power_series_ring_element._solve_linear_de
> (sage/rings/power_series_ring_element.c:11103)
> File "power_series_ring_element.pyx", line 1650, in
> sage.rings.power_series_ring_element._solve_linear_de
> (sage/rings/power_series_ring_element.c:11124)
> File "/Users/robert/sage/sage-3.1.3/local/lib/python2.5/site-
> packages/sage/rings/polynomial/polynomial_ring.py", line 252, in __call__
> return C(self, x, check, is_gen, construct=construct)
> File "polynomial_integer_dense_flint.pyx", line 224, in
> sage.rings.polynomial.polynomial_integer_dense_flint.Polynomial_integer_dense_flint.__init__
> (sage/rings/polynomial/polynomial_integer_dense_flint.cpp:4981)
> File "parent.pyx", line 293, in sage.structure.parent.Parent.__call__
> (sage/structure/parent.c:3828)
> File "parent.pyx", line 284, in sage.structure.parent.__call__
> (sage/structure/parent.c:3712)
> File "rational.pyx", line 2288, in sage.rings.rational.Q_to_Z._call_
> (sage/rings/rational.c:14682)
> TypeError: no conversion of this rational to integer
> }}}
New description:
This works
{{{
sage: R.<x> = ZZ[]
sage: sqrt(1+x+O(x^5))
1 + 1/2*x - 1/8*x^2 + 1/16*x^3 - 5/128*x^4 + O(x^5)
}}}
One would expect this to work:
{{{
sage: R.<x> = ZZ[[]]
sage: exp(x+O(x^5))
Traceback (most recent call last):
File "<ipython console>", line 1, in <module>
File "/Users/robert/sage/current/local/lib/python2.5/site-
packages/sage/calculus/calculus.py", line 8415, in __call__
return x.exp()
File "power_series_ring_element.pyx", line 1383, in
sage.rings.power_series_ring_element.PowerSeries.exp
(sage/rings/power_series_ring_element.c:9850)
File "power_series_ring_element.pyx", line 1305, in
sage.rings.power_series_ring_element.PowerSeries.solve_linear_de
(sage/rings/power_series_ring_element.c:9707)
File "power_series_ring_element.pyx", line 1648, in
sage.rings.power_series_ring_element._solve_linear_de
(sage/rings/power_series_ring_element.c:11103)
File "power_series_ring_element.pyx", line 1650, in
sage.rings.power_series_ring_element._solve_linear_de
(sage/rings/power_series_ring_element.c:11124)
File "/Users/robert/sage/sage-3.1.3/local/lib/python2.5/site-
packages/sage/rings/polynomial/polynomial_ring.py", line 252, in __call__
return C(self, x, check, is_gen, construct=construct)
File "polynomial_integer_dense_flint.pyx", line 224, in
sage.rings.polynomial.polynomial_integer_dense_flint.Polynomial_integer_dense_flint.__init__
(sage/rings/polynomial/polynomial_integer_dense_flint.cpp:4981)
File "parent.pyx", line 293, in sage.structure.parent.Parent.__call__
(sage/structure/parent.c:3828)
File "parent.pyx", line 284, in sage.structure.parent.__call__
(sage/structure/parent.c:3712)
File "rational.pyx", line 2288, in sage.rings.rational.Q_to_Z._call_
(sage/rings/rational.c:14682)
TypeError: no conversion of this rational to integer
}}}
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4748#comment:3>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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