#11753: Fix step=0 in (x)srange
---------------------------------+------------------------------------------
Reporter: ppurka | Owner: jason, was
Type: defect | Status: positive_review
Priority: minor | Milestone: sage-4.7.2
Component: graphics | Keywords: srange xsrange
division_by_zero
Work_issues: | Upstream: N/A
Reviewer: Dmitrii Pasechnik | Author: P. Purkayastha
Merged: | Dependencies:
---------------------------------+------------------------------------------
Changes (by newvalueoldvalue):
* reviewer: => Dmitrii Pasechnik
* author: => P. Purkayastha
Old description:
> The following command
> {{{
> plot(x,3,3)
> }}}
> generates the following error:
> {{{
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "_sage_input_4.py", line 10, in <module>
> exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8
> -*-\\n" +
> _support_.preparse_worksheet_cell(base64.b64decode("cGxvdCh4LDMsMyk="),globals())+"\\n");
> execfile(os.path.abspath("___code___.py"))
> File "", line 1, in <module>
>
> File "/tmp/tmpezK4rJ/___code___.py", line 3, in <module>
> exec compile(u'plot(x,_sage_const_3 ,_sage_const_3 )
> File "", line 1, in <module>
>
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/decorators.py", line 573, in wrapper
> return func(*args, **kwds)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/decorators.py", line 432, in wrapper
> return func(*args, **options)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/plot/plot.py", line 3032, in plot
> G = funcs.plot(*args, **original_opts)
> File "expression.pyx", line 8023, in
> sage.symbolic.expression.Expression.plot
> (sage/symbolic/expression.cpp:31185)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/decorators.py", line 573, in wrapper
> return func(*args, **kwds)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/decorators.py", line 432, in wrapper
> return func(*args, **options)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/plot/plot.py", line 3051, in plot
> G = _plot(funcs, (xmin, xmax), *args, **kwds)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/plot/plot.py", line 3154, in _plot
> data = generate_plot_points(f, xrange, plot_points,
> adaptive_tolerance, adaptive_recursion, randomize)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/plot/plot.py", line 4154, in generate_plot_points
> data = srange(*ranges[0], include_endpoint=True)
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/misc.py", line 1149, in srange
> L =
> list(xsrange(start,end,step,universe,check,include_endpoint,endpoint_tolerance))
> File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
> packages/sage/misc/misc.py", line 1236, in xsrange
> count = (end-start)/step
> ZeroDivisionError: float division
> }}}
> The error seems to be in (x)srange in devel/sage/sage/misc/misc.py.
> Attached is a patch which raises a ValueError when the start point and
> end point of a plot are the same. The patches are to
> devel/sage/sage/{misc,plot}/misc.py and devel/sage/sage/plot/plot.py.
>
> I forgot to mention earlier: the errors that are generated with this
> patch for (x)srange() are essentially the same errors that python gives
> when (x)range() is called with step 0.
>
> Apply 11753-fix_div_by_zero.patch to devel/sage
New description:
The following command
{{{
plot(x,3,3)
}}}
generates the following error:
{{{
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_4.py", line 10, in <module>
exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8
-*-\\n" +
_support_.preparse_worksheet_cell(base64.b64decode("cGxvdCh4LDMsMyk="),globals())+"\\n");
execfile(os.path.abspath("___code___.py"))
File "", line 1, in <module>
File "/tmp/tmpezK4rJ/___code___.py", line 3, in <module>
exec compile(u'plot(x,_sage_const_3 ,_sage_const_3 )
File "", line 1, in <module>
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/decorators.py", line 573, in wrapper
return func(*args, **kwds)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/decorators.py", line 432, in wrapper
return func(*args, **options)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/plot/plot.py", line 3032, in plot
G = funcs.plot(*args, **original_opts)
File "expression.pyx", line 8023, in
sage.symbolic.expression.Expression.plot
(sage/symbolic/expression.cpp:31185)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/decorators.py", line 573, in wrapper
return func(*args, **kwds)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/decorators.py", line 432, in wrapper
return func(*args, **options)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/plot/plot.py", line 3051, in plot
G = _plot(funcs, (xmin, xmax), *args, **kwds)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/plot/plot.py", line 3154, in _plot
data = generate_plot_points(f, xrange, plot_points,
adaptive_tolerance, adaptive_recursion, randomize)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/plot/plot.py", line 4154, in generate_plot_points
data = srange(*ranges[0], include_endpoint=True)
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/misc.py", line 1149, in srange
L =
list(xsrange(start,end,step,universe,check,include_endpoint,endpoint_tolerance))
File "/home/punarbasu/Installations/sage-4.7/local/lib/python2.6/site-
packages/sage/misc/misc.py", line 1236, in xsrange
count = (end-start)/step
ZeroDivisionError: float division
}}}
The error seems to be in [`x`]`srange()` in `sage/misc/misc.py`. Attached
is a patch which raises a `ValueError` when the start point and end point
of a plot are the same. The patches are to `sage/{misc,plot}/misc.py` and
`sage/plot/plot.py`.
I forgot to mention earlier: The errors that are generated with this patch
for [`x`]`srange()` are essentially the same errors that Python gives when
[`x`]`range()` is called with step 0.
----
Apply only [attachment:11753-fix_div_by_zero.patch] to the Sage library.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11753#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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