Compilare: user.cpp: In function ‘double apm2(double)’: user.cpp:79:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < M.size(); ++ i){ ^ user.cpp: In function ‘int main()’: user.cpp:96:15: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(A == 0) ^