Sorry for disturbing, I solved the problem. For if some body is interested: I use a class symbol_numeric derived from symbol. the expression that was offending was conceptually of the type my_expression = symbol * (my_symbol_numeric) +my_symbol_numeric the result didn't simplified. I suppose this is CORRECT BEHAVIOR. My fault was the typecast removing it or changing it to symbol_numeric, solves the problem. That's why my_expression.subs(lst(symbol(my_symbol_numeric)==0,my_symbol_numeric ==0)) was needed. Now standard simplification my_expression.subs(my_symbol_numeric ==0) works. so I think the problem was related, although in a really involved manner, to the symbol factory known issue referred in GiNaC's Tutorial. Thank you again, Javier On Wed, Jul 27, 2011 at 11:09 PM, Javier Ros <jros@unavarra.es> wrote:

Jens,

On Wed, Jul 27, 2011 at 8:41 PM, Jens Vollinga <jens.vollinga@googlemail.com> wrote:

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Hi Javier,

your information is a bit confusing. First you write:

I'm sorry.

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On 27.07.2011 19:23, Javier Ros wrote:

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the following trivial simplifications

my_ex.subs((*ddq_i)==0)

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go wrong no correct substitution, in different ways

then you write:

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Interestingly  until now I was simplifying correctly using

my_ex.subs((*ddq_i)==0)

You can disregard this sentence.

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So, once it goes wrong, then it goes well?!? Did you upgrade GiNaC to a newer version, maybe?

Disregard the my_ex.subs((*ddq_i)==0) goes OK thing,

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Anyway, could you, if possible, send a complete code example to explain your problem? It is hard to guess what the problem might be, otherwise.

It's going to take some time to isolate, as I'm using a library that I've build on top of GiNaC to generate the offending my, but I'll try if I can reproduce it using plain GiNaC, writing and reading it back in a plain GiNaC program.

In any case I suppose that the trivial simplifications

my_ex.subs((*ddq_i)==0)

my_ex.subs(*ddq_i==0)

my_ex.subs(symbol(*ddq_i)==0)

should coincident with these

my_ex.subs(lst(symbol(*ddq_i)==0,*ddq_i==0))

my_ex.subs(lst(symbol(*ddq_i)==0,(*ddq_i)==0))

But unfortunately only the last two are working.

Do you agree that this is not normal behavior?.

Thank you,

Javier