On Oct 13, 2009, at 1:24 PM, lutusp wrote:
> I'm aware there has been some discussion of this issue in the past,
> but I would like to renew it. I understand that canonical DE notation
> isn't on everyone's short list of high priorities, but I think
> students and those with little Sage exposure would appreciate the
> ability to enter a textbook equation with few changes.
>
> It would be great to see this user entry:
>
> y'(x) + y - 1
>
> Automatically become this Sage syntax:
>
> diff(y,x) + y - 1
>
> And I wrote this simple Python code to do it:
>
> import de
>
> def parsediffeq(s):
> """
> Convert differential equation syntax
> from standard to Sage:
> y'(x) -> y.diff(x,1)
> y''(x) -> y.diff(x,2)
> etc.
> """
> for n in range(1,6):
> ds = "'" * n
> s = re.sub("(\w+)%s\((\w+)\)" % ds,"\\1.diff(\\2,%d)" % n,s)
> return s
>
> The conversion is not very difficult, and it would make working with
> DEs a great deal easier, especially for those unfamiliar with Sage
> and/
> or who want to solve published problems expressed in canonical DE
> notation.
>
> Does this issue have any traction? I sometimes read posts from people
> who won't use Sage for lack of this syntax (perhaps not many).
I agree that this notation is nice. One issue with this approach is
that the single quote is already used in Python. For example,
sage: u'(x) + y'
u'(x) + y'
sage: type(_)
<type 'unicode'>
sage: r'''(t)'''
'(t)'
How would one distinguish between the uses?
- Robert
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