C++ Copy Constructor error: Assignment of member 'Fraction::numerator' in read-only object : I am having a problem with this error.

My Header file:
    #include <iostream>

    using namespace std;

    class Fraction
    {

    private:
        double numerator;
        double denominator;
    public:
        Fraction();
        ~Fraction();
        Fraction(const Fraction& c);
        Fraction(double,double);
        //setter
        void setNumerator(double newnumerator);
        void setDenominator(double newdenominator);
        //getter
        double getNumerator();
        double getDenominator();

        //friend overlaoding operators

        friend ostream& operator<<(ostream& os, Fraction f);

    };

My CPP file:

    #include <iostream>
    #include "Fraction.h"

    using namespace std;

    Fraction::Fraction()
    {
        cout<<"Empty constructor called"<<endl;
    }

    Fraction::~Fraction()
    {
        cout<<"Deconstructor called"<<endl;
    }

    Fraction::Fraction(const Fraction& c)
    {
        c.numerator = numerator;
        c.denominator = denominator;
    }

    Fraction::Fraction(double newnumerator, double newdenominator)
    {
        numerator = newnumerator;
        denominator = newdenominator;
    }

    void Fraction::setNumerator(double newnumerator)
    {
        numerator = newnumerator;
    }

    void Fraction::setDenominator(double newdenominator)
    {
        denominator = newdenominator;
    }

    double Fraction::getNumerator()
    {
        return numerator;
    }

    double Fraction::getDenominator()
    {
        return denominator;
    }

    ostream& operator<<(ostream& os, Fraction f)
    {
         os<<f.numerator<<"/"<<f.denominator<<endl;
         return os;

    }

My testcpp.file:

    #include <iostream>
    #include "Fraction.h"

    using namespace std;

    int main()
    {
    	Fraction f1;

        cout<<f1;

        return 0;
    }

When I run this code I get this error message:

    Fraction.cpp: In copy constructor ‘Fraction::Fraction(const Fraction&)’:
    Fraction.cpp:20:17: error: assignment of member ‘Fraction::numerator’ in   read-only object
         c.numerator = numerator;
                 ^
    Fraction.cpp:21:19: error: assignment of member ‘Fraction::denominator’ in  read-only object
         c.denominator = denominator;
                   ^

PS: Once I left out the copy copy constructor and tried if the rest really works, but I get the same error message for the overloading operator(cin>>).

Thank you very much.