In some circumstances, "Stein's trick" may help [1]:
class myint:
def eval(self, s, globals, locals):
_temp = locals['Integer']
locals['Integer'] = float
ans = python.eval(preparse(s), globals, locals)
locals['Integer'] = _temp
return ans
Examples, in separate cells:
%myint()
print type(45)
print 500 / 1000, 1000 / 1000
print 500 / 1000., 1000 / 1000.
<type 'float'>
0.5 1.0
0.500000000000000 1.00000000000000
print type(45)
print 500 / 1000, 1000 / 1000
print 500 / 1000., 1000 / 1000.
<type 'sage.rings.integer.Integer'>
1/2 1
0.500000000000000 1.00000000000000
Modular arithmetic, Python 'int', and matplotlib.pyplot examples at [2].
I don't why the extra point at the origin shows up.
[1] https://groups.google.com/group/sage-devel/msg/e53caae140cef7df
[2] http://www.sagenb.org/home/pub/563/
Robert Bradshaw wrote:
> On May 22, 2009, at 2:00 PM, Nick Alexander wrote:
>
>>> We do this to avoid the (large) overhead of re-creating constants in
>>> the bodies of loops, functions, etc. Perhaps we need to detect the
>>> Integer=xxx line explicitly?
>> Doing this accurately is equivalent to the halting problem.
>
> Yep. Detecting an assignment to Integer (RealNumber, ...) should be
> sufficient to eliminate most headaches, especially as this simple
> assignment is what we tell users to do.
>
>> This is what pragmas are for, but do we really want to start
>> supporting all
>> these compiler features? When is sage no longer python?
>
> A long time ago, e.g. when we started using Integer(...) to wrap
> integer literals. Despite my work on the preparser, I'm all for
> keeping it minimal.
>
> - Robert
>
>
> >
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