#4973: [with patch, positive review] rewrite the function __getitem__ in
matrix0.pyx to support slices better, negative indices, and be faster
----------------------+-----------------------------------------------------
Reporter: mabshoff | Owner: jason
Type: defect | Status: assigned
Priority: major | Milestone: sage-3.3
Component: misc | Resolution:
Keywords: |
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Comment (by robertwb):
Here's the actual generated code for {{{x,y = t}}}
{{{
if (PyTuple_CheckExact(__pyx_v_t) && PyTuple_GET_SIZE(__pyx_v_t) == 2)
{
PyObject* tuple = __pyx_v_t;
__pyx_2 = PyTuple_GET_ITEM(tuple, 0);
Py_INCREF(__pyx_2);
Py_DECREF(__pyx_v_x);
__pyx_v_x = __pyx_2;
__pyx_2 = 0;
__pyx_2 = PyTuple_GET_ITEM(tuple, 1);
Py_INCREF(__pyx_2);
Py_DECREF(__pyx_v_y);
__pyx_v_y = __pyx_2;
__pyx_2 = 0;
}
else {
[generic code]
}
}}}
If {{{t}}} is declared to be a tuple, half of the first check shouldn't be
needed (I don't think this optimization is in place yet). So it should be
as fast as type check + length check + PyTuple_GET_ITEM. In any case, it's
faster than indexing not using PyTyple_GET_ITEM.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4973#comment:20>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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