#10105: cremona_letter_code does not handle erronous input gracefully.
-------------------------------+--------------------------------------------
Reporter: drkirkby | Owner: cremona
Type: defect | Status: new
Priority: minor | Milestone: sage-4.6
Component: elliptic curves | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------------+--------------------------------------------
Although I'm not a mathematician, I believe from reading the help page and
looking at the examples, the Sage command {{{cremona_letter_code}}} should
probably only work for non-negative integers. However, this is not the
case.
{{{
sage: cremona_letter_code(23.23) # Invalid input, gives output.
'x'
sage: cremona_letter_code(-3) # Invalid input, hangs using lots of CPU
time.
}}}
Any attempt to send erroneous input to a command should generate an error
message.
There seems to be three problems with this.
* Negative integers hang Sage, using lots of CPU time.
* The documentation says "integers" but I think it should say "non-
negative integers" - at least all the examples are either 0 or positive
integers.
* Floating point numbers produce output, despite the fact the
documentation says the argument should be an integer.
This was found by using Fuzz Testing
http://en.wikipedia.org/wiki/Fuzz_testing
where one purposely supplies invalid input, to check how software behaves.
http://www.ibm.com/developerworks/java/library/j-fuzztest.html
says ''Fuzz testing is a simple technique that can have a profound effect
on your code quality.''
I've marked it as a minor priority, as clearly its not a huge bug. But it
would be worth fixing it.
Dave
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10105>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
