IndexError in integral_points_count of Polyhedron

[seblabbe]

With latte_int installed:

$ sage -experimental
...
latte_int...............................1.7.3 (1.7.3)
...

I get:

sage: eqns = [[-10, 0, 1], [-10, 1, 0]]
sage: P = Polyhedron(ieqs=[], eqns=eqns)
sage: P.integral_points_count()
...
sage/geometry/polyhedron/base.pyc in integral_points_count(self, verbose)
   4259             raise RuntimeError("LattE integrale failed (exit code {}) to execute {}".format(ret_code, ' '.join(args)) + err.strip())
   4260
-> 4261         return Integer(ans.splitlines()[-1])
   4262
   4263     def integral_points(self, threshold=100000):

IndexError: list index out of range

Same error with:

sage: P = Polyhedron(ieqs=[], eqns=[[-11,0,2],[-10,1,0]])
sage: P.vertices()
(A vertex at (10, 11/2),)

The culprit might be the empty string:

sage: "".splitlines()[-1]
---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-1-7faf349df14a> in <module>()
----> 1 "".splitlines()[-Integer(1)]

IndexError: list index out of range

CC: @mkoeppe

Component: geometry

Keywords: days79

Author: Sébastien Labbé

Branch/Commit: ce82303

Reviewer: Moritz Firsching, Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/21491

[seblabbe]

comment:2

Just to say that in both cases, latte_int gets the answer right.

1 in this case:

sage: P = Polyhedron(ieqs=[], eqns=[[-10, 0, 1], [-10, 1, 0]])
sage: P.integral_points_count(verbose=True)
This is LattE integrale 1.7.3
Available from http://www.math.ucdavis.edu/~latte/
...
Ax <= b, given as (b|-A):
=========================
[]

Ax = b, given as (b|-A):
========================
[-10 0 1]
[-10 1 0]

The number of lattice points is 1.
---------------------------------------------------------------------------
Traceback (most recent call last)
...
IndexError: list index out of range

0 in this case:

sage: P = Polyhedron(ieqs=[], eqns=[[-11,0,2],[-10,1,0]])
sage: P.integral_points_count(verbose=True)
This is LattE integrale 1.7.3
Available from http://www.math.ucdavis.edu/~latte/
...
Ax <= b, given as (b|-A):
=========================
[]

Ax = b, given as (b|-A):
========================
[-11 0 2]
[-10 1 0]

The number of lattice points is 0.
---------------------------------------------------------------------------
Traceback (most recent call last)
...
IndexError: list index out of range

[seblabbe]

Commit: 27948e8

[seblabbe]

Author: Sébastien Labbé

[seblabbe]

New commits:

27948e8

21491: using file numOfLatticePoints for integral_points_count method

[seblabbe]

Branch: u/slabbe/21491

[mo271]

comment:4

This seems to work!

[seblabbe]

comment:6

Thanks for the review!

[seblabbe]

Changed keywords from none to days79

[seblabbe]

Reviewer: Moritz Minzlaff

[tscrim]

comment:8

Since opening a file takes ~10x longer than a try/except block, I suggest the following:

        try:
            return Integer(ans.splitlines()[-1])
        except IndexError:
            with open(SAGE_TMP+'/numOfLatticePoints', 'r') as f:
                return Integer(f.read())

[mo271]

Changed reviewer from Moritz Minzlaff to Moritz Firsching

[sagetrac-git]

Changed commit from 27948e8 to 347aa90

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

347aa90

21491: catching the IndexError instead

[tscrim]

comment:12

Thanks.

[tscrim]

Changed reviewer from Moritz Firsching to Moritz Firsching, Travis Scrimshaw

[vbraun]

comment:13

Documentation doesn't build, see patchbot.

[tscrim]

comment:14

Trivial fix TESTS:: -> TESTS:, so I'm allowing myself to set this back to positive review.

---

New commits:

b090df5	Merge branch 'u/slabbe/21491' of trac.sagemath.org:sage into u/tsrcim/21491
ce82303	Fixing doc for #21491.

[tscrim]

Changed commit from 347aa90 to ce82303

[tscrim]

Changed branch from u/slabbe/21491 to u/tscrim/21491

[seblabbe]

comment:15

Thank you for fixing this Travis.

Sébastien

[vbraun]

Changed branch from u/tscrim/21491 to ce82303