On Fri, May 9, 2008 at 9:28 AM, Marshall Hampton <[EMAIL PROTECTED]> wrote:
>
> I'm not sure I agree that this is a bug. After using the name "var"
> in the loop, the value of var is y. y is a symbolic variable, and
> when evaluated at the string "x,y" it returns "x,y"; this seems like
> desirable behavior (to have string-valued functions seems OK to me).
>
> Or another way to put it: if the above behavior is a bug, then I think
> the following would be as well:
> sage: x,y = var("x,y")
> sage: y(2)
> 2
>
> Or perhaps I am missing something.
> -M. Hampton
There is an issue with the design, though it is arguable what it is.
Notice that var('x') acts as the identity function irregardless of the input,
where as var('x')^2 coerces its input to the SymbolicRing.
sage: x = var('x')
sage: x('hello world')
'hello world'
sage: type(x('hello world'))
<type 'str'>
sage: (x^2)('hello world')
hello^2*world^2
sage: type((x^2)('hello world'))
<class 'sage.calculus.calculus.SymbolicArithmetic'>
sage: x,y=var("x,y")
I thus think the right fix would be for var('x') to also coerce its input
to the symbolic ring. So, in the original question var('x,y') would
give an error since:
sage: SR('x,y')
Traceback (most recent call last):
...
TypeError: Malformed expression: x, !!! y
By the way, what's up with the !!! in the error message? That looks
very weird.
What do you think.
-- william
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/sage-support
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
