Hi,
On Tue, Jun 23, 2009 at 1:33 PM, Mikie<thephantom6...@hotmail.com> wrote:
> The values are coming in as strings and I am converting them to
> calculus type. It is kind of working, but when I put 2*x^2-x or
> 2*x**2-x I get "not a valid Python identifier. What is real strange
> is If I put
> "x-2*x^2" it works.
> Is there anyway to get the Sage preparser to work in the Python
> script.
Your best bet for that type of thing is to pass the string into SR
which will parse the expression.
sage: SR('2*x^2-x')
2*x^2 - x
sage: SR('2*x**2-x')
2*x^2 - x
sage: SR('x-2*x^2')
-2*x^2 + x
To access the preparser, you can do something like:
sage: sage.misc.preparser.preparse('x^2')
'x**Integer(2)'
Note that you get a string back. You need to eval() that to get an
object back. Note that there are security risks using eval(). That's
why it's safer to use the parser in SR.
--Mike
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