ZeroDivisionError popping in sage/schemes/elliptic_curves/padics.py doctest

[Dima Pasechnik]

On MacOSX 10.5, Sage 5.4.beta1 (with new GAP 4.5.6 spkg) I get 

(any idea what it could be? Endianness?)

This is the only doctest failing on this platform.

sage -t --long -force_lib "devel/sage/sage/schemes/elliptic_curves/padics.py"

**********************************************************************

File "/usr/local/src/sage/sage-5.4.beta1/devel/sage/sage/schemes/elliptic_curves/padics.py", line 799:

    sage: for prec in range(2, max_prec):                 # long time

          assert E.padic_height_via_multiply(Integer(5), prec)(P) == full   # long time

Exception raised:

    Traceback (most recent call last):

      File "/usr/local/src/sage/sage-5.4.beta1/local/bin/ncadoctest.py", line 1231, in run_one_test

        self.run_one_example(test, example, filename, compileflags)

      File "/usr/local/src/sage/sage-5.4.beta1/local/bin/sagedoctest.py", line 38, in run_one_example

        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)

      File "/usr/local/src/sage/sage-5.4.beta1/local/bin/ncadoctest.py", line 1172, in run_one_example

        compileflags, 1) in test.globs

      File "<doctest __main__.example_7[15]>", line 2, in <module>

        assert E.padic_height_via_multiply(Integer(5), prec)(P) == full   # long time

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/padics.py", line 829, in padic_height_via_multiply

        sigma = self.padic_sigma_truncated(p, N=adjusted_prec, E2=E2, lamb=lamb)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/padics.py", line 1206, in padic_sigma_truncated

        E2 = self.padic_E2(p, N-2, check_hypotheses=False)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/padics.py", line 1425, in padic_E2

        frob_p = self.matrix_of_frobenius(p, prec, check, check_hypotheses, algorithm).change_ring(Integers(p**prec))

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/padics.py", line 1565, in matrix_of_frobenius

        Q, p, adjusted_prec, trace)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/monsky_washnitzer.py", line 1651, in matrix_of_frobenius

        F1_reduced = reduce_all(Q, p, F1_coeffs, offset)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/monsky_washnitzer.py", line 1024, in reduce_all

        exact_form = reduce_negative(Q, p, coeffs, offset, exact_form)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/schemes/elliptic_curves/monsky_washnitzer.py", line 788, in reduce_negative

        a[0] = base_ring(lift(a[0]) / (j+1))

      File "parent.pyx", line 804, in sage.structure.parent.Parent.__call__ (sage/structure/parent.c:7228)

      File "coerce_maps.pyx", line 82, in sage.structure.coerce_maps.DefaultConvertMap_unique._call_ (sage/structure/coerce_maps.c:3547)

      File "coerce_maps.pyx", line 77, in sage.structure.coerce_maps.DefaultConvertMap_unique._call_ (sage/structure/coerce_maps.c:3449)

      File "/usr/local/src/sage/sage-5.4.beta1/local/lib/python/site-packages/sage/rings/finite_rings/integer_mod_ring.py", line 925, in _element_constructor_

        return integer_mod.IntegerMod(self, x)

      File "integer_mod.pyx", line 177, in sage.rings.finite_rings.integer_mod.IntegerMod (sage/rings/finite_rings/integer_mod.c:3504)

      File "integer_mod.pyx", line 1530, in sage.rings.finite_rings.integer_mod.IntegerMod_gmp.__init__ (sage/rings/finite_rings/integer_mod.c:14993)

      File "rational.pyx", line 2473, in sage.rings.rational.Rational.__mod__ (sage/rings/rational.c:19891)

      File "integer.pyx", line 5485, in sage.rings.integer.Integer.inverse_mod (sage/rings/integer.c:32726)

    ZeroDivisionError: Inverse does not exist.

**********************************************************************

1 items had failures:

   1 of  17 in __main__.example_7

***Test Failed*** 1 failures.

For whitespace errors, see the file /Users/dima/.sage//tmp/padics_41488.py

         [79.0 s]

 

----------------------------------------------------------------------

The following tests failed:

        sage -t --long -force_lib "devel/sage/sage/schemes/elliptic_curves/padics.py"

Total time for all tests: 79.0 seconds

[Dima Pasechnik]

and if I try running this code at the Sage prompt, it works. Some strange testing framework failure...