Possible to improve "inconsistency" between notations for exponentiation?

[sebe...@spawar.navy.mil]

Python uses "**" for exponentiation.
Sage syntax uses the much nicer "^".
Won't this lead to problems/confusion since Sage uses python code to
define functions but not to *invoke* those functions?

Chris

[Justin C. Walker]

Changing "^" to "**" would improve the consistency, not the
inconsistency :-}

I know what you mean, but I think we're wedded to the difference. It
does admittedly cause some issues, but in the long run, I believe it
is more consistent with the aims that the Sage developers have set for
Sage.

Justin

--
Justin C. Walker, Curmudgeon at Large
Institute for the Absorption of Federal Funds
-----------
My wife 'n kids 'n dogs are gone,
I can't get Jesus on the phone,
But Ol' Milwaukee's Best is my best friend.
-----------

[sebe...@spawar.navy.mil]

On Nov 1, 11:30 pm, "Justin C. Walker" <jus...@mac.com> wrote:
> Changing "^" to "**" would improve the consistency, not the  
> inconsistency  :-}
>
> I know what you mean, but I think we're wedded to the difference.

What about if Sage modified Python syntax slightly?
For example, what if Sage added pre-processing code to replace "^"
with "**" before feeding the Sage/Python code to the Python
interpreter?

This would mean that Sage coders could use "^" everywhere including in
Python code.
Then Sage could allow both "^" and "**" everywhere.

e.g.

def my_sage_square_function(x):
return x^2

One potential problem I can forsee with this is if someone really
wanted to do XOR in Sage/Python code. But even in that case they
could use alternatives.

Chris

[mabshoff]

On Nov 2, 12:08 pm, "seber...@spawar.navy.mil"

<seber...@spawar.navy.mil> wrote:
> On Nov 1, 11:30 pm, "Justin C. Walker" <jus...@mac.com> wrote:
>
> > Changing "^" to "**" would improve the consistency, not the  
> > inconsistency  :-}
>
> > I know what you mean, but I think we're wedded to the difference.
>
> What about if Sage modified Python syntax slightly?
> For example, what if Sage added pre-processing code to replace "^"
> with "**" before feeding the Sage/Python code to the Python
> interpreter?

Sage already does that via its preparser:

sage: x^2
x^2
sage: x**2
x^2
sage: preparse("x^2")
'x**Integer(2)'

I.e.. any time you there is a "^" in input it is replaced by "**". You
can turn the preparser off and then use "^" to signify XOR.

> This would mean that Sage coders could use "^" everywhere including in
> Python code.
> Then Sage could allow both "^" and "**" everywhere.
>
> e.g.
>
> def my_sage_square_function(x):
>             return x^2
>
> One potential problem I can forsee with this is if someone really
> wanted to do XOR in Sage/Python code.  But even in that case they
> could use alternatives.
>
> Chris

Cheers,

Michael

[sebe...@spawar.navy.mil]

On Nov 2, 12:14 pm, mabshoff <mabsh...@googlemail.com> wrote:
> Sage already does that via its preparser:
>
> sage: x^2
> x^2
> sage: x**2
> x^2
> sage: preparse("x^2")
> 'x**Integer(2)'

Yes but I don't think you are claiming that Python code can use ^ for
exponentials are you?
Actually I'm moving towards opinion that I should just use "**"
everywhere.

Alternatively, I could avoid Python code everywhere now that Stein
pointed out to me how to define functions w/o Python code...

my_function(t) = 4*t -9

cs

[William Stein]

On Sun, Nov 2, 2008 at 4:41 PM, sebe...@spawar.navy.mil
<sebe...@spawar.navy.mil> wrote:
>
>
>
> On Nov 2, 12:14 pm, mabshoff <mabsh...@googlemail.com> wrote:
>> Sage already does that via its preparser:
>>
>> sage: x^2
>> x^2
>> sage: x**2
>> x^2
>> sage: preparse("x^2")
>> 'x**Integer(2)'
>
> Yes but I don't think you are claiming that Python code can use ^ for
> exponentials are you?
> Actually I'm moving towards opinion that I should just use "**"
> everywhere.

That is a consistent way to go. Plus it will work in Fortran :-)

> Alternatively, I could avoid Python code everywhere now that Stein
> pointed out to me how to define functions w/o Python code...
>
> my_function(t) = 4*t -9

There might be some confusion. If you're writing code in the notebook
or the command line, you can do this and it will work fine:

sage: def f(x):
....: return x^2
....:
sage: f(10)
100

I.e., even "python functions" get their body's preparsed, so ^ works. The
only problem is if you put code in an external .py file.

Keep persisting -- I think there's some failure to communicate here there
will get clarified with persistence. And the trail of this conversation will be
useful to other people who find it later.

William