bug in supersingular module

[williamstein]

sage: X = SupersingularModule(389)
sage: X
Module of supersingular points on X_0(1)/F_389 over Integer Ring
sage: X.basis()
Traceback (most recent call last):
...
AttributeError: 'SupersingularModule' object has no attribute 'free_module'

Apply attachment: trac_4306.patch​, attachment: trac_4306-doctest.2.patch

CC: @loefflerd

Component: modular forms

Keywords: sd51

Author: William Stein

Reviewer: Alex Ghitza, David Loeffler

Merged: sage-5.12.beta2

Issue created by migration from https://trac.sagemath.org/ticket/4306

[williamstein]

comment:1

The attached patch doesn't implement elements of supersingular modules -- that isn't implemented yet at all! But it implements a free_module() method so that now the above input results in a NotImplementedError, which is the right behavior when something isn't implemented.

[williamstein]

Attachment: trac_4306.patch.gz

[aghitza]

comment:2

With the patch applied, I'm getting

sage -t -long "modular/ssmod/ssmod.py"                      
**********************************************************************
File "/opt/sage-4.3.1/devel/sage-main/sage/modular/ssmod/ssmod.py", line 38:
    sage: t = X.T(2).matrix()            # long time (but still less than a minute!)
Exception raised:
    Traceback (most recent call last):
      File "/home/ghitza/sage-devel/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/home/ghitza/sage-devel/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/home/ghitza/sage-devel/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_0[9]>", line 1, in <module>
        t = X.T(Integer(2)).matrix()            # long time (but still less than a minute!)###line 38:
    sage: t = X.T(2).matrix()            # long time (but still less than a minute!)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modular/hecke/module.py", line 1343, in T
        return self.hecke_operator(n)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modular/hecke/module.py", line 1330, in hecke_operator
        return self.hecke_algebra().hecke_operator(n)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modular/hecke/module.py", line 325, in hecke_algebra
        self.__hecke_algebra = algebra.HeckeAlgebra(self)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modular/hecke/algebra.py", line 136, in HeckeAlgebra
        k = (M, M.basis_matrix())
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modular/hecke/module.py", line 828, in basis_matrix
        return self.free_module().basis_matrix()
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/modules/free_module.py", line 2087, in basis_matrix
        A = MAT.identity_matrix()
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/matrix/matrix_space.py", line 944, in identity_matrix
        A = self(0)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/matrix/matrix_space.py", line 395, in __call__
        return self.matrix(entries, copy=copy, coerce=coerce, rows=rows)
      File "/home/ghitza/sage-devel/local/lib/python/site-packages/sage/matrix/matrix_space.py", line 1087, in matrix
        return self.__matrix_class(self, entries=x, copy=copy, coerce=coerce)
      File "matrix_rational_dense.pyx", line 149, in sage.matrix.matrix_rational_dense.Matrix_rational_dense.__cinit__ (sage/matrix/matrix_rational_dense.c:4931)
    MemoryError: out of memory allocating a matrix
**********************************************************************
File "/opt/sage-4.3.1/devel/sage-main/sage/modular/ssmod/ssmod.py", line 39:
    sage: t.nrows()                      # long time
Exception raised:
    Traceback (most recent call last):
      File "/home/ghitza/sage-devel/local/bin/ncadoctest.py", line 1231, in run_one_test
        self.run_one_example(test, example, filename, compileflags)
      File "/home/ghitza/sage-devel/local/bin/sagedoctest.py", line 38, in run_one_example
        OrigDocTestRunner.run_one_example(self, test, example, filename, compileflags)
      File "/home/ghitza/sage-devel/local/bin/ncadoctest.py", line 1172, in run_one_example
        compileflags, 1) in test.globs
      File "<doctest __main__.example_0[10]>", line 1, in <module>
        t.nrows()                      # long time###line 39:
    sage: t.nrows()                      # long time
    NameError: name 't' is not defined
**********************************************************************
1 items had failures:
   2 of  18 in __main__.example_0
***Test Failed*** 2 failures.
For whitespace errors, see the file /home/ghitza/.sage//tmp/.doctest_ssmod.py
	 [21.4 s]
 
----------------------------------------------------------------------
The following tests failed:


	sage -t -long "modular/ssmod/ssmod.py"
Total time for all tests: 21.4 seconds

[aghitza]

comment:3

OK, it seems like the underlying issue in the last comment has disappeared. With sage-5.10:

sage: X = SupersingularModule(389)
sage: X.basis()                   
---------------------------------------------------------------------------
NotImplementedError                       Traceback (most recent call last)
<ipython-input-2-30f7d3cb5e51> in <module>()
----> 1 X.basis()

/opt/ghitza/sage/local/lib/python2.7/site-packages/sage/modular/hecke/module.pyc in basis(self)
    865             return self.__basis
    866         except AttributeError:
--> 867             self.__basis = self.gens()
    868         return self.__basis
    869 

/opt/ghitza/sage/local/lib/python2.7/site-packages/sage/structure/parent_gens.so in sage.structure.parent_gens.ParentWithGens.gens (sage/structure/parent_gens.c:3292)()

/opt/ghitza/sage/local/lib/python2.7/site-packages/sage/modular/hecke/module.pyc in gen(self, n)
   1342             (1,17)
   1343         """
-> 1344         return self(self.free_module().gen(n))
   1345 
   1346     def hecke_matrix(self, n):

/opt/ghitza/sage/local/lib/python2.7/site-packages/sage/structure/parent.so in sage.structure.parent.Parent.__call__ (sage/structure/parent.c:7916)()

NotImplementedError: 

I am adding a reviewer patch that doctests this.

[aghitza]

Attachment: trac_4306-doctest.patch.gz

[aghitza]

Author: William Stein

[aghitza]

Reviewer: Alex Ghitza

[aghitza]

Changed keywords from none to sd51

[loefflerd]

Alex's patch with a better commit message

[loefflerd]

comment:5

Attachment: trac_4306-doctest.2.patch.gz

I edited Alex's patch to add a better commit message. Other than that I think this is fine.

[loefflerd]

Changed reviewer from Alex Ghitza to Alex Ghitza, David Loeffler

[jdemeyer]

Merged: sage-5.12.beta2