// Define some arrays of doubles 

double a[3] = { 11, 12, 13 }; 

double b[3] = { 21, 22, 23 };

// Initialize vectors from the

// double arrays 

Vector v1 = a; 

Vector v2 = b;

// Add the two matrices. 

Vector v3 = v1 + v2;

The Vector class has been defined with all of the appropriate arithmetic

operations so that it can be treated as a built-in type. It is even 

possible to define conversion operators so that we can convert the

Vector to a double,we get the magnitude, or norm, of the Vector:

double norm = (double) v3;