Pattern matching in GiNaC CVS

[Do Hoang Son]

On Mon, 18 Jun 2001, Christian Bauer wrote:

> On Mon, Jun 18, 2001 at 03:36:39PM +0200, Do Hoang Son wrote:
> > > > > c=subs(b,log($1)==Log($1));
> > > > unknown function 'Log'
> > > > ...
> > > > Of course, Log() is undefined one.
> > > 
> > > Correct. So?
> > 
> > It would be nice if such a substitution is accepted in ginsh. 
> 
> But there is no function named "Log" in GiNaC. What is ginsh supposed to do?
> Modify inifcns.h/.cpp and recompile GiNaC?

Hmmm, I don't know.
Just look at Maple 

> c:=ln(x*y)*z;
> subs(ln=foo,c);
foo(x*y)*z

or in Mathematica

In[1]:= c=Log[x*y]*z
 
Out[1]= z Log[x y]
 
In[2]:= c//. Log[a__]-> foo[a]
  
Out[2]= z foo[x y]

There is not any problem there.
One offent uses this trick to get rid of troubles that caused by a
difined/internal functions.
 
Don't tell me if it is stupid or not. 
Just want to know if this well known feature is possible to be implemented
in ginsh?

Son