#include <iostream>
using namespace std;
 
const int N = 3;
 
typedef double T;
 
T a[N], b[N];
T c[N];
 
void add(T* z, T* x, T* y) // z[i] = x[i] + y[i]
{
    for (int i = 0; i < N; i++) {
        z[i] = x[i] + y[i];
    }
}
void mult (T* z, T c, T* x) // z[i] = c *x[i]
{
    for (int i = 0; i < N; i++) {
        z[i] = c * x[i];
    }
}
void print(string name, T* x)
{
    cout << name << " ( ";
    for (int i = 0; i < N; i++) {
        cout << x[i];
        if (i < N - 1) cout << ", "; 
    }
    cout << " )" << endl;
}
#include <cmath> // funkce sqrt
 
T size(T* x) // velikost vektoru x
{
	T v = 0;
	for (int i = 0; i < N; i++) 
	{
		v = v + x[i] * x[i];
	}
	return sqrt(v);
}
 
T dot (T* x, T *y) // skalarni soucin
{
	T v = 0;
	for (int i = 0; i < N; i++)
	{
		v = v + x[i] * y[i];
	}
	return v;
}
 
T uhel(T* a, T* b)
{
	return acos ( dot(a, b) / ( size(a) * size (b) ) );
}
 
 
int main()
{
    for (int i = 0; i < N; i++) {
        a[i] = 1.1 * i;
        b[i] = 10 * i;
    }
    print("acko", a);
    print("becko", b);
    mult(b, 2, b); // b = 2*b
    add (c, a, b);
    print("cecko", c);
    cout << "O.K.";
}