Eroare de compilare: user.cpp:11:16: error: ‘float y1’ redeclared as different kind of symbol float x1,x2,x3,y1,y2,y3; ^ In file included from /usr/include/features.h:357:0, from /usr/include/i386-linux-gnu/c++/4.8/bits/os_defines.h:39, from /usr/include/i386-linux-gnu/c++/4.8/bits/c++config.h:420, from /usr/include/c++/4.8/iosfwd:38, from /usr/include/c++/4.8/ios:38, from /usr/include/c++/4.8/istream:38, from /usr/include/c++/4.8/fstream:38, from user.cpp:1: /usr/include/i386-linux-gnu/bits/mathcalls.h:243:1: error: previous declaration of ‘double y1(double)’ __MATHCALL (y1,, (_Mdouble_)); ^ user.cpp: In function ‘int main()’: user.cpp:22:44: error: invalid operands of types ‘float’ and ‘double(double)throw ()’ to binary ‘operator*’ delta = x1*y2*1 + x2*y3*1 + x3*y1*1 - y1*x2*1 - y2*x3*1 - y3*x1*1; ^ user.cpp:22:54: error: invalid operands of types ‘double(double)throw ()’ and ‘float’ to binary ‘operator*’ delta = x1*y2*1 + x2*y3*1 + x3*y1*1 - y1*x2*1 - y2*x3*1 - y3*x1*1; ^ user.cpp:26:11: error: assignment of function ‘double y1(double)’ y1=y2; ^ user.cpp:26:11: error: cannot convert ‘float’ to ‘double(double)throw ()’ in assignment user.cpp:36:11: error: cannot bind ‘std::basic_istream<char>::__istream_type {aka std::basic_istream<char>}’ lvalue to ‘std::basic_istream<char>&&’ in>>x1>>y1; ^ In file included from /usr/include/c++/4.8/fstream:38:0, from user.cpp:1: /usr/include/c++/4.8/istream:872:5: error: initializing argument 1 of ‘std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&&, _Tp&) [with _CharT = char; _Traits = std::char_traits<char>; _Tp = double(double)throw ()]’ operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x) ^ user.cpp:39:36: error: invalid operands of types ‘float’ and ‘double(double)throw ()’ to binary ‘operator*’ delta = x1*y2*1 + x2*y3*1 + x3*y1*1 - y1*x2*1 - y2*x3*1 - y3*x1*1; ^ user.cpp:39:46: error: invalid operands of types ‘double(double)throw ()’ and ‘float’ to binary ‘operator*’ delta = x1*y2*1 + x2*y3*1 + x3*y1*1 - y1*x2*1 - y2*x3*1 - y3*x1*1; ^