On Nov 8, 9:09 am, Michael Orlitzky <mich...@orlitzky.com> wrote:
> On 11/07/11 21:03, kcrisman wrote:
>
>
>
> > So are you saying that Python and Piecewise functions will no longer
> > behave correctly if this behavior goes from warning to error? It
> > would be great if you had a "toy" example with full code; maybe there
> > is a workaround that needs to become standard practice here...
>
> For piecewise, the problem and toy example are easy. The first
> evaluation gives the warning, the second an error.
>
> $ cat piecewise_test.py
> #!/home/mjo/bin/sage
>
> from sage.all import *
>
> x = SR.symbol('x', domain='real')
>
> interval0 = (0, 0.5)
> function0 = 4.0*(x - 0.5)**2
> f = piecewise([[interval0, function0]])
>
> print "f(1/2):"
> print f(1/2)
> print ""
Note that this goes away if you instead define
sage: f0(x) = 4.0*(x-0.5)^2
(I mean after restarting Sage; the deprecation warning only will show
up once in any case.)
So I'm not sure this is a problem per se, though that doesn't mean
there isn't another problem lurking. I agree that we would have to
make sure people didn't do this, but the documentation for piecewise
functions already expects people to use f(x)= notation, except if
inserted directly in like Piecewise([[(0,1),x^2]]) or something.
> print "f(x=1/2):"
> print f(x=1/2)
> print ""
Hmm, yeah - piecewise functions don't have a subs() method nor do they
allow this notation. That is a separate problem, and it does seem
like a problem, since
sage: g = x^2
sage: g(x=2)
4
sage: g(2)
DeprecationWarning: Subst...
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