I get the error message, that I make an undefined reference to a class function

Question

I made vector class in c++ with having the class in a new module, and having a separate header file. If I call any of the class functions from the main function, i get the undefined reference error, even though i have included the header file everywhere

vec2d.h

#ifndef VEC2D_H
#define VEC2D_H

class vector{
private: double x, y;

public: vector(double x, double y);
        vector(int x, int y);
        vector();

        double getX()const;
        double getY()const;
        double getR()const;
        double getPhi()const;

        void Print() const;

        void setX(double x);
        void setY(double y);
        void setR(double r);
        void setPhi(double phi);
        vector sum(const vector inv)const;
};

double Abs(const vector v);
vector sum(const vector a, const vector b);
vector minusz(const vector a, const vector b);
double dotprod(const vector a, const vector b);
vector operator *(const double alpha, const vector v);
vector operator -(const vector a, const vector b);

#endif // VEC2D_H

vec2d.cpp

#include <cmath>
#include <cstdio>
#include "vec2d.h"

vector::vector(double x, double y)
{
    this->x = x;
    this->y = y;
}

vector::vector(int x, int y)
{
    this->x = (double)x;
    this->y = (double)y;
}

vector::vector()
{
    this->x = 0;
    this->y = 0;
}

double vector::getX()const
{
    return x;
}

double vector::getY()const
{
    return y;
}

double vector::getR()const
{
    return sqrt(x*x + y*y);
}

double vector::getPhi()const
{
    return atan2(y, x);
}

void vector::Print() const
{
    printf("[ %lf, %lf ] \n", x, y);
}

void vector::setX(double x)
{
    this->x = x;
}

void vector::setY(double y)
{
    this->y = y;
}

void vector::setR(double r)
{
    x = r * cos(getPhi());
    y = r * sin(getPhi());
}

void vector::setPhi(double phi)
{
    x = getR() * cos(phi);
    y = getR() * sin(phi);
}

vector vector::sum(const vector inv)const
{
    vector outv;
    outv.x = x + inv.x;
    outv.y = y + inv.y;
    return outv;
}


double Abs(const vector v)
{
    return v.getR();
}

vector sum(const vector a, const vector b)
{
    vector outv;
    outv.setX( a.getX() + b.getX() );
    outv.setY( a.getY() + b.getY() );

    return outv;
}

vector minusz(const vector a, const vector b)
{
    vector outv;
    outv.setX( a.getX() - b.getX() );
    outv.setY( a.getY() - b.getY() );
    return outv;
}

double dotprod(const vector a, const vector b)
{
    return a.getX() * b.getX() + a.getY() * b.getY();
}

vector operator *(const double alpha, const vector v)
{
    return vector(alpha * v.getX(), alpha * v.getY() );
}

vector operator -(const vector a, const vector b)
{
    return vector(a.getX() - b.getX(), a.getY() - b.getY());
}

main.cpp

#include <cstdio>
#include <cmath>
#include "vec2d.h"
#include "PontToltes.h"

using namespace std;

int main()
{
    vector v(2,3);

    ptoltes a(1, 2, 2);

    v.Print();

    return 0;
}

Could you help me please,Its probably a rookie mistake, but I don't get it.