When I call MixedIntegerLinearProgram I get the error AssertionError: The given source does not contain 'def'. This occurs both when calling any of its methods, like MixedIntegerLinearProgram.show(), and when viewing its documentation I get a backtrace in place of the documentation.
I am running Mac OS 10.11 (El Capitan). I get the same error in my emacs sage interpreter and Terminal. I recently tried to upgrade from sage 6.5 to 6.9 and the build failed; ask me about that if you think it's related. sage is installed to my home directory. Please ask if more details are needed.
Below is a full backtrace for a command I tried.
sage: g=Graph({0:[1,3],1:[0,2],2:[1,3],3:[2,0]})
sage: g
Graph on 4 vertices
sage: plot(g) #I checked my graph
sage: g.vertex_cut(0,2)
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
<ipython-input-17-b3f3e7c533ca> in <module>()
----> 1 g.vertex_cut(Integer(0),Integer(2))
/Users/alejo/sage/local/lib/python2.7/site-packages/sage/graphs/generic_graph.pyc in vertex_cut(self, s, t, value_only, vertices, solver, verbose)
5525
5526 # Some vertices belong to part 1, some others to part 0
-> 5527 p.add_constraint(v[s] == 0)
5528 p.add_constraint(v[t] == 1)
5529
/Users/alejo/sage/src/sage/numerical/mip.pyx in sage.numerical.mip.MIPVariable.__getitem__ (build/cythonized/sage/numerical/mip.c:16841)()
2560 :meth:`MixedIntegerLinearProgram.new_variable`.
2561 """
-> 2562
2563 def __init__(self, parent, mip, vtype, name, lower_bound, upper_bound):
2564 r"""
/Users/alejo/sage/src/sage/numerical/mip.pyx in sage.numerical.mip.MixedIntegerLinearProgram.__call__ (build/cythonized/sage/numerical/mip.c:3714)()
490 self._linear_constraints_parent = LinearConstraintsParent(LF)
491 return self._linear_constraints_parent
--> 492
493 def __call__(self, x):
494 """
/Users/alejo/sage/src/sage/numerical/mip.pyx in sage.numerical.mip.MixedIntegerLinearProgram.linear_functions_parent (build/cythonized/sage/numerical/mip.c:3376)()
453 # Check for redundant constraints
454 self._check_redundant = check_redundant
--> 455 if check_redundant:
456 self._constraints = list()
457
/Users/alejo/sage/src/sage/misc/cachefunc.pyx in sage.misc.cachefunc.CachedFunction.__call__ (build/cythonized/sage/misc/cachefunc.c:4678)()
917 True
918 sage: f(y) is not f(x)
--> 919 True
920
921 """
/Users/alejo/sage/src/sage/misc/cachefunc.pyx in sage.misc.cachefunc.CachedFunction.argfix_init (build/cythonized/sage/misc/cachefunc.c:3203)()
719 """
720 A = ArgumentFixer(self.f,classmethod=self.is_classmethod)
--> 721 self._argument_fixer = A
722 if self.key:
723 self._fix_to_pos = self._fix_to_pos_and_create_key
/Users/alejo/sage/src/sage/misc/function_mangling.pyx in sage.misc.function_mangling.ArgumentFixer.__init__ (build/cythonized/sage/misc/function_mangling.c:862)()
122 cdef public tuple _default_tuple
123 def __init__(self, f, classmethod = False):
--> 124 try:
125 arg_names, varargs, varkw, defaults = sage_getargspec(f)
126 except AttributeError:
/Users/alejo/sage/local/lib/python2.7/site-packages/sage/misc/sageinspect.pyc in sage_getargspec(obj)
1382 source = sage_getsource(obj, is_binary=True)
1383 if source:
-> 1384 return inspect.ArgSpec(*_sage_getargspec_cython(source))
1385 else:
1386 func_obj = obj
/Users/alejo/sage/local/lib/python2.7/site-packages/sage/misc/sageinspect.pyc in _sage_getargspec_cython(source)
1007 """
1008 defpos = source.find('def ')
-> 1009 assert defpos > -1, "The given source does not contain 'def'"
1010 s = source[defpos:].strip()
1011 while s:
AssertionError: The given source does not contain 'def'
