// vector.h
//
// A class for double vectors
//
// J.Liu, R.Cali
// ColoState, Jan. 2007 -- Feb. 2008


#ifndef VECTOR_H
#define VECTOR_H

#include <iostream>

class Vector {
public: 
   Vector(int numElts, double a=0);  // Constructor, all elements a or 0
   Vector(int numElts, double *data);  // Constructor with given data
   Vector(const Vector &v);  // Copy constructor, very useful
   Vector &operator=(const Vector &v);  // Copy assignment
      // The copy constructor looks silly willy but is ABSOLUTELY necessary
      // It is implicitly used by functions returnig a vector
      // Meanwhile the destructor is also implicitly called by those functions
   ~Vector() {delete[] p; p=0; n=0;}  // Destructor
   void resize(int numElts);  // Resize the vector
   double &operator[](int i) const {return p[i];}  // 0<=i<n
   double &operator()(int i) const {return p[i-1];}  // 1<=i<=n
   int size() const {return n;}
   double l0norm() const;  // l_infty norm
   double l1norm() const;  // l_1 norm
   double l2norm() const;  // l_2 norm
   Vector get(int i, int length);  // get subvector
   Vector replace(int i, const Vector &v);  // replace subvector
   Vector &operator+=(const Vector&);  // v += w
   Vector &operator-=(const Vector&);  // v -= w
   Vector operator-() const;  // Unary -
   void save2file(char fn[20]) const;  // save to a data file
friend Vector operator+(const Vector&, const Vector&);  // v = v1 + v2;
friend Vector operator-(const Vector&, const Vector&);  // v = v1 + v2;
// friend Vector operator*(const Vector&, const Vector&);
// v = v1*v2, componentwise
// friend Vector operator/(const Vector&, const Vector&);
// v = v1/v2, componentwise
friend Vector operator*(const double, const Vector&);  // Scalar-vector multiplication
friend double operator*(const Vector&, const Vector&);  // Dot product
friend double dotProd(const Vector&, const Vector&);  // Dot product
friend std::ostream &operator<<(std::ostream&strm, const Vector&v);
private: 
   int n;
   double *p;
};

#endif  // VECTOR_H