Ok, thanks!

On Sep 10, 8:55 pm, Burcin Erocal <[email protected]> wrote:
> Hi Kees,
>
> On Fri, 10 Sep 2010 08:10:45 -0700 (PDT)
>
>
>
> KvS <[email protected]> wrote:
> > Dear all,
>
> > I'm sorry I have yet again something to bother you with. Running the
> > following few lines:
>
> > eq=5-e^x
> > print "1:",eq.substitute(x=3*x)
> > print "2:",eq.substitute(x=log(x))
>
> > yields the output (Sage 4.5.2 with Ubuntu):
>
> > 1: -e^(3*x) + 5
> > 2: -log(x) + 5
>
> > So 1 is fine, but it seems that to get to 2 Sage actually substitutes
> > twice no: 5-e^x -> 5-x -> 5-log(x). I had expected it would just give
> > me 5-x rather, is it a bug or a feature?
>
> Thanks for reporting the problem.
>
> This looks like a bug in GiNaC, the library we use for the symbolic
> expressions.
>
> ginsh - GiNaC Interactive Shell (ginac V1.5.7)
>   __,  _______  Copyright (C) 1999-2010 Johannes Gutenberg University
> Mainz, (__) *       | Germany.  This is free software with ABSOLUTELY
> NO WARRANTY. ._) i N a C | You are welcome to redistribute it under
> certain conditions. <-------------' For details type `warranty;'.
>
> Type ?? for a list of help topics.> subs(5-exp(x),x==log(x));
>
> 5-log(x)
>
> I opened a ticket for this:
>
> http://trac.sagemath.org/sage_trac/ticket/9891
>
> Cheers,
> Burcin

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