C2780 when using the STL copy algorithm

Greetings, I'm trying to design a "copy constructor", everything was fine until I came up with the copy algorithm and I have obtained a C2780 because apparently it only recognizes 2 of 3 arguments for copy ...

#include<iostream>
#include<algorithm>

using namespace std;

// a very simplified vector of doubles
class vector {
    int sz; // the size
    double* elem; // a pointer to the elements
public:
    vector(int s) :sz{ s }, elem{ new double[s] } 
    { for (int i = 0; i<sz; ++i) elem[i] = 0.0; } // constructor
    vector(const vector&); // copy constructor: define copy
    ~vector() { delete[] elem; } // destructor
    int size() const { return sz; } // the current size
    double get(int n) const { return elem[n]; } // access: read
    void set(int n, double v) { elem[n] = v; } // access: write
};

vector::vector(const vector& arg)
// allocate elements, then initialize them by copying
    :sz{ arg.sz }, elem{ new double[arg.sz] }
{
    copy(arg, arg + sz, elem); // std::copy(); see §B.5.2
}

int main()
{
    vector v(5);
    for (int i = 0; i < v.size(); ++i) {
        v.set(i, 1.1*i);
        cout << "v[" << i << "]==" << v.get(i) << '\n';
    }
}

Thank you very much for your time.