#16755: PPL LP solver does not accept rationals
--------------------------------------+------------------------
Reporter: jdemeyer | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.3
Component: linear programming | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
--------------------------------------+------------------------
Description changed by jdemeyer:
Old description:
> Given that PPL natively works with rationals, this should work:
> {{{
> sage: p = MixedIntegerLinearProgram(solver="PPL")
> sage: x = p.new_variable(nonnegative=True)
> sage: p.add_constraint(x[0] + x[1] <= 1/2)
> sage: p.set_objective(x[0])
> sage: p.solve()
> ---------------------------------------------------------------------------
> TypeError Traceback (most recent call
> last)
> <ipython-input-10-082b726ace8d> in <module>()
> ----> 1 p.solve()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/numerical/mip.so in
> sage.numerical.mip.MixedIntegerLinearProgram.solve
> (build/cythonized/sage/numerical/mip.c:10574)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/numerical/backends/ppl_backend.so in
> sage.numerical.backends.ppl_backend.PPLBackend.solve
> (build/cythonized/sage/numerical/backends/ppl_backend.c:5346)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/numerical/backends/ppl_backend.so in
> sage.numerical.backends.ppl_backend.PPLBackend.init_mip
> (build/cythonized/sage/numerical/backends/ppl_backend.c:2284)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/libs/ppl.so in sage.libs.ppl.Linear_Expression.__richcmp__
> (build/cythonized/sage/libs/ppl.cpp:17640)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/libs/ppl.so in sage.libs.ppl._make_Constraint_from_richcmp
> (build/cythonized/sage/libs/ppl.cpp:23124)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/libs/ppl.so in sage.libs.ppl.Linear_Expression.__cinit__
> (build/cythonized/sage/libs/ppl.cpp:15675)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/rings/integer.so in sage.rings.integer.Integer.__init__
> (build/cythonized/sage/rings/integer.c:7650)()
>
> /usr/local/src/sage-config/local/lib/python2.7/site-
> packages/sage/rings/rational.so in sage.rings.rational.Rational._integer_
> (build/cythonized/sage/rings/rational.c:20851)()
>
> TypeError: no conversion of this rational to integer
> }}}
New description:
This should work (even though PPL doesn't seem to provide an easy
interface for inputting rationals):
{{{
sage: p = MixedIntegerLinearProgram(solver="PPL")
sage: x = p.new_variable(nonnegative=True)
sage: p.add_constraint(x[0] + x[1] <= 1/2)
sage: p.set_objective(x[0])
sage: p.solve()
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
<ipython-input-10-082b726ace8d> in <module>()
----> 1 p.solve()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/numerical/mip.so in
sage.numerical.mip.MixedIntegerLinearProgram.solve
(build/cythonized/sage/numerical/mip.c:10574)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/numerical/backends/ppl_backend.so in
sage.numerical.backends.ppl_backend.PPLBackend.solve
(build/cythonized/sage/numerical/backends/ppl_backend.c:5346)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/numerical/backends/ppl_backend.so in
sage.numerical.backends.ppl_backend.PPLBackend.init_mip
(build/cythonized/sage/numerical/backends/ppl_backend.c:2284)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/libs/ppl.so in sage.libs.ppl.Linear_Expression.__richcmp__
(build/cythonized/sage/libs/ppl.cpp:17640)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/libs/ppl.so in sage.libs.ppl._make_Constraint_from_richcmp
(build/cythonized/sage/libs/ppl.cpp:23124)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/libs/ppl.so in sage.libs.ppl.Linear_Expression.__cinit__
(build/cythonized/sage/libs/ppl.cpp:15675)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/rings/integer.so in sage.rings.integer.Integer.__init__
(build/cythonized/sage/rings/integer.c:7650)()
/usr/local/src/sage-config/local/lib/python2.7/site-
packages/sage/rings/rational.so in sage.rings.rational.Rational._integer_
(build/cythonized/sage/rings/rational.c:20851)()
TypeError: no conversion of this rational to integer
}}}
--
--
Ticket URL: <http://trac.sagemath.org/ticket/16755#comment:1>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" 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/sage-trac.
For more options, visit https://groups.google.com/d/optout.
