Compilare: user.c: In function ‘main’: user.c:21:5: warning: implicit declaration of function ‘fabs’ [-Wimplicit-function-declaration] fprintf(fout,"%lf\n",fabs(a/2)); ^ user.c:21:26: warning: incompatible implicit declaration of built-in function ‘fabs’ [enabled by default] fprintf(fout,"%lf\n",fabs(a/2)); ^ user.c:9:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%d",&n); ^ user.c:10:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%lf%lf",&xp,&yp); ^ user.c:15:15: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin,"%lf%lf",&x,&y); ^