# parametric_plot gives "IndexError: list index out of range" in SageMath 8.1-11 on Arch Linux

I've been attempting to plot a parabola, but I keep running into an error from the "expression_comparisons.py" file as an "index out of range" error. Help? My OS is Arch Linux, using the Cinnamon DE, and version 8.1-11 of Sagemath. Attempted code:

```
sage: var('t')
sage: parametric_plot((t,t^2),(t,-4,4))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_11.py", line 10, in <module>
exec compile(u'open("___code___.py","w").write("# -*- coding: utf-8 -*-\\n" + _support_.preparse_worksheet_cell(base64.b64decode("cGFyYW1ldHJpY19wbG90KCh0LHReMiksKHQsLTQsNCkp"),globals())+"\\n"); execfile(os.path.abspath("___code___.py"))
File "", line 1, in <module>
File "/tmp/tmpwjIIYE/___code___.py", line 3, in <module>
exec compile(u'parametric_plot((t,t**_sage_const_2 ),(t,-_sage_const_4 ,_sage_const_4 ))
File "", line 1, in <module>
File "/usr/lib/python2.7/site-packages/sage/misc/decorators.py", line 564, in wrapper
return func(*args, **options)
File "/usr/lib/python2.7/site-packages/sage/plot/plot.py", line 2621, in parametric_plot
return plot(funcs, *args, **kwargs)
File "/usr/lib/python2.7/site-packages/sage/misc/decorators.py", line 564, in wrapper
return func(*args, **options)
File "/usr/lib/python2.7/site-packages/sage/plot/plot.py", line 1950, in plot
G = _plot(funcs, *args, **kwds)
File "/usr/lib/python2.7/site-packages/sage/plot/plot.py", line 2067, in _plot
funcs, ranges = setup_for_eval_on_grid(funcs, [xrange], options['plot_points'])
File "/usr/lib/python2.7/site-packages/sage/plot/misc.py", line 150, in setup_for_eval_on_grid
return fast_float(funcs, *vars,**options), [tuple(range+[range_step]) for range,range_step in zip(ranges, range_steps)]
File "sage/ext/fast_eval.pyx", line 1384, in sage.ext.fast_eval.fast_float (build/cythonized/sage/ext/fast_eval.c:11037)
File "sage/ext/fast_eval.pyx", line 1399, in sage.ext.fast_eval.fast_float (build/cythonized/sage/ext/fast_eval.c:11258)
File "sage/ext/fast_callable.pyx", line 465, in sage.ext.fast_callable.fast_callable (build/cythonized/sage/ext/fast_callable.c:4634)
File "sage/symbolic/expression.pyx", line 11679, in sage.symbolic.expression.Expression._fast_callable_ (build/cythonized/sage/symbolic/expression.cpp:66334)
File "/usr/lib/python2.7/site-packages/sage/symbolic/expression_conversions.py", line 1757, in fast_callable
return FastCallableConverter(ex, etb)()
File "/usr/lib/python2.7/site-packages/sage/symbolic/expression_conversions.py", line 218, in __call__
return self.arithmetic(ex, operator)
File "/usr/lib/python2.7/site-packages/sage/symbolic/expression_conversions.py", line 1670, in arithmetic
exponent = operands[1]
IndexError: list index out of range
```

Welcome to Ask Sage! Thank you for your question!

Strange; the command in the question should work without problem... Can you try as follows?

WorksForMe (TM) on version 8.2.beta8 running on Debian testing.

If you have access to another machine with a different platform, it might be worth testing it on that platform. It might be specific to

yourbinary. Did you built it yourself, or was it packaged in Arch ?It works for me as well, both with Sage 8.1 and Sage 8.2.rc1 (OS: Ubuntu 16.04).

@cookchar: if the answer by @arojas solves your question, please accept it by clicking the "accept" (tick mark) button next to it! This will mark your question as solved and the answer as accepted.