Francesco Biscani wrote:

I'm using ginac 1.3.4 and trying to transform from std::string to ex. I'm using the small test program present in the FAQ:

--------------------------------------------------------- #include <iostream> #include <string> #include <stdexcept> #include <ginac/ginac.h> using namespace std; using namespace GiNaC;

int main() { symbol x("x"); string s;

cout << "Enter an expression containing 'x': "; getline(cin, s);

try { ex e(s, lst(x)); cout << "The derivative of " << e << " with respect to x is "; cout << e.diff(x) << ".\n"; } catch (exception &p) { cerr << p.what() << endl; } } ---------------------------------------------------------

The problem is that it does not work at all. Example output:

Enter an expression containing 'x': 5+x The derivative of x with respect to x is 1

I.e., "5+x" is parsed simply as x. With different expressions I get other wierd errors, like:

Enter an expression containing 'x': 5+3*x^2 The derivative of 2 with respect to x is 0.

syntax error, unexpected T_EOF, expecting ']' or ',' at

As strange as it sounds, ginsh seems not to have these problems

Type ?? for a list of help topics.

...

diff(x^2+sin(x),x);

2*x+cos(x)

...

I'm using gcc 4.1.1 on Gentoo. ginac was compiled with "-O2" c(xx)flag.

Thanks very much for ginac! I'm writing an algebraic manipulator software for Poisson series (celestial mechanics), and ginac would really help me manipulate the series' coefficients (instead of writing some ad-hoc representation for them). I hope this issue can be resolved.

I'm unable to reproduce your problem using either Debian/testing (gcc 4.1.2-prerelease) or Debian/stable (gcc 3.3.5). Over here, it works as expected. I'm CCing ginac-list, maybe someone there has a similar system and can reproduce your problem? The behavior you describe sounds too weird to be true. I recommend first using another system or compiler version in order to get a clue where it is coming from. Luck -richy. -- Richard B. Kreckel <http://www.ginac.de/~kreckel/>