#10112: random_prime does not handle erroneous input gracefully - it hangs
-----------------------------+----------------------------------------------
Reporter: drkirkby | Owner: was
Type: defect | Status: new
Priority: major | Milestone: sage-4.6.1
Component: number theory | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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As noted at #10111 and
http://groups.google.com/group/sage-
devel/browse_thread/thread/6e8d6f28c915830d?hl=en
{{{random_prime()}}} is not well documented.
But {{{random_prime()}}} is also broken for some erroneous input. Programs
should always handle poor input properly, which is the case of Sage
probably means generating an error message.
{{{
sage: random_prime(0,True,-1) # Hangs
sage: random_prime(0,False,-1) # Hangs
sage: random_prime(1,0,-23) # Hangs
sage: random_prime(-12,0,-12) # Hangs
sage: random_prime(0, proof=False, lbound=-12) # Hangs
}}}
Having a negative lower bound can cause the function to hang, but this is
not always the case, as the example below shows. Here an error message is
generated.
{{{
sage: random_prime(-12,0,-4)
---------------------------------------------------------------------------
ValueError Traceback (most recent call
last)
/export/home/drkirkby/sage-4.6.alpha3/<ipython console> in <module>()
/export/home/drkirkby/sage-4.6.alpha3/local/lib/python2.6/site-
packages/sage/rings/arith.pyc in random_prime(n, proof, lbound)
1144 n = ZZ(n)
1145 if n < lbound:
-> 1146 raise ValueError, "n must be greater than lbound:
%s"%(lbound)
1147 elif n == 2:
1148 return ZZ(n)
ValueError: n must be greater than lbound: -4
}}}
Dave
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10112>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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