Dear all,

I got a problem with the function subs, and I am not sure it is a possible bug or not, 

but it seems counterintuitive. 

Here is the code to reproduce the case:

//------------------------------------------------

#include "ginac/ginac.h"

using namespace std;

using namespace GiNaC;

int main() {

    symbol s("s");

    ex t = subs(1/s,s==1/s, subs_options::no_pattern);

    cout << t << endl;

    return 0;

}

//------------------------------------------------

The output is 1/s instead of s.

PS: if I remove the subs_options::no_pattern, the output is s as expected.

and I have a look at the source code of basic::subs, it seems it comes from the following code:

that is, the final substitutions on the new object as a whole,

//------------------------------------------------

// Perform substitutions on the new object as a whole
return copy->subs_one_level(m, options);

//------------------------------------------------

Thanks very much in advance.

Best regards!

Feng