Dear Burcin,
Just one quick question about patches, I have just changed the
expression.pyx file and ran another make (which took not so much
time). But it does not seem to work. Is this simple way of applying
patch enough or do I have to go through the mercurial system ?
Thanks !
On 11 juin, 17:12, Burcin Erocal <bur...@erocal.org> wrote:
> Hi Nicolas,
>
> On Thu, 11 Jun 2009 07:07:50 -0700 (PDT)
>
>
>
> Nicolas <nicolas.fresseng...@gmail.com> wrote:
>
> > Hi all,
>
> > I am trying, in sage 4.0, to write a class that inherits from the new
> > sage.symbolic.expression.Expression class. I have not found any
> > precise signature for the __init__ method of that class so I suppose I
> > am doing something wrong : things seem to work, except for the
> > substitute stuff.
>
> > Here is an example of what I mean :
>
> > ______________________________________
> > class test(Expression):
> > def __init__(self,eq):
> > Expression.__init__(self,SR,eq)
>
> > f=function("f")
> > g=function("g")
> > a=f(x)
> > b=test(f(x))
> > testa=a.substitute_function(f,g)
> > testb=b.substitute_function(f,g)
> > ______________________________________
> > sage: testa
> > g(x)
> > sage: testb
> > f(x)
> > sage:
>
> > Anyone to help me out ?
>
> I don't think the __init__ function in Expression is usable as it is.
> Here is the code:
>
> def __init__(self, SR, x=0):
> cdef GEx exp
> GEx_construct_pyobject(exp, x)
> GEx_construct_ex(&self._gobj, exp)
> self._parent = SR
>
> The line with GEx_construct_pyobject() coerces the symbolic expression
> you give it to a constant numeric object. Then, in your construction, b
> becomes a constant.
>
> sage: b.operator() # this returns None since it's a constant
> sage: t.operator()
> f
>
> After applying the patch below, the following works:
>
> ----------------------------------------------------------------------
> | Sage Version 4.0.1, Release Date: 2009-06-06 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
> Loading Sage library. Current Mercurial branch is: la
> sage: from sage.symbolic.expression import Expression
> sage: class esub(Expression):
> ....: def __init__(self, parent, val):
> ....: Expression.__init__(self, parent, val)
> ....:
> sage: f = function('f')
> sage: g = function('g')
> sage: t = f(x)
> sage: b = esub(SR, t)
> sage: b.substitute_function(f, g)
> g(x)
>
> This still doesn't solve your problem though, most methods of
> Expression will return Expression objects.
>
> sage: type(b.substitute_function(f, g))
> <type 'sage.symbolic.expression.Expression'>
>
> Can you explain your application a little?
>
> Cheers,
> Burcin
>
> diff --git a/sage/symbolic/expression.pyx b/sage/symbolic/expression.pyx
> --- a/sage/symbolic/expression.pyx
> +++ b/sage/symbolic/expression.pyx
> @@ -212,9 +212,8 @@
> sage: sage.symbolic.expression.Expression(SR, 5)
> 5
> """
> - cdef GEx exp
> - GEx_construct_pyobject(exp, x)
> - GEx_construct_ex(&self._gobj, exp)
> + cdef Expression exp = self.coerce_in(x)
> + GEx_construct_ex(&self._gobj, exp._gobj)
> self._parent = SR
>
> def __dealloc__(self):
--~--~---------~--~----~------------~-------~--~----~
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