Hello, I am using Numerical Recipes routines and I am trying to call this function void mrqmin(Vec_I_DP &x, Vec_I_DP &y, Vec_I_DP &sig, Vec_IO_DP &a, Vec_I_BOOL &ia, Mat_O_DP &covar, Mat_O_DP &alpha, DP &chisq, void funcs(const DP, Vec_I_DP &, DP &, Vec_O_DP &), DP &alamda); and I would like to call it with funcs being a member function pointer of one of my class. I can declare the member as static but then I cannot access member variable, which is the goal here. Someone suggested to use boost to solve the problem. His solution is here http://www.numerical-recipes.com/forum/showthread.php?s=&threadid=526 I tried to implement this but the result is this error: cannot convert `boost::function<void ()(double, const Vec_I_DP&, double&, Vec_O_DP&), std::allocator<void> >' to `void (*)(DP, const Vec_I_DP&, DP&, Vec_O_DP&)' for argument `9' to `void NR::mrqmin(const Vec_I_DP&, const Vec_I_DP&, const Vec_I_DP&, Vec_IO_DP&, const Vec_I_BOOL&, Mat_O_DP&, Mat_O_DP&, DP&, void (*)(DP, const Vec_I_DP&, DP&, Vec_O_DP&), DP&)' Any idea how I could do that? Thanks -- Philippe