#11753: Fix step=0 in (x)srange
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Reporter: ppurka | Owner: jason, was
Type: defect | Status: needs_work
Priority: minor | Milestone: sage-4.7.2
Component: graphics | Keywords: srange xsrange division_by_zero
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by dimpase):
Replying to [comment:13 ppurka]:
> Replying to [comment:12 dimpase]:
> > Replying to [comment:11 ppurka]:
> > > Replying to [comment:10 dimpase]:
> > > > The condition {{{step == 0}}} you check looks worrisome. From a
glance over the code it's not clear whether {{{step}}} cannot be a float,
and if it is a float, then such a test does not make much sense.
> > >
> > > Should be fixed now.
> >
> > Ever written "real" numerical code?
> >
> > {{{min(range_steps) == float(0)}}} won't fly. You need something like
{{{min(range_steps)<C*sys.float_info.epsilon}}}, for {{{C}}}
> > something like 2 or 10...
>
> Is this needed? Something like {{{plot(sqrt(x), 0,
sys.float_info.epsilon**2)}}} works just fine.
oops, sorry. It looks like plot works with arbitrary precision floats from
sage.rings.real_mpfr, not with hardware plots!
Then indeed, your previous version was just fine. (no need to do any
float(0) either)
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11753#comment:14>
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