// Oldham, Jeffrey D.
// 2000 Feb 21
// CS1321

// Mathematical Vector Implemented Using Vectors

// We choose to implement a mathematical vector class MVector using
// the STL vector<double> container class.
//
// For example, the mathematical vector (3 4.3 5) could be stored in a 
// vector v having three components: v[0] = 3.0, v[1] = 4.3, v[2] = 5.0.

// Below is a portion of the MVector class definition.  The portion
// that you should implement is indicated by "ADD SOMETHING HERE"
// comments.  In deciding what to add, consider the following questions.
// 1) What should its name be?  overloaded?  operator?
// 2) Should it be ordinary, static, or a friend.

// Feel free to define other functions as necessary.


#include <vector>


class MVector {
public:
  // Our MVector's size is measured using "size_type".
  typedef vector<double>::size_type size_type;

  // constructors
  // Write three constructors:
  // 1) taking no arguments
  // 2) taking one argument of the MVector's length
  // 3) copying another MVector

  // ADD SOMETHING HERE

  // element access: query, change
  double at(const size_type i) const { return v[i]; }
  void set(const size_type i, const double d) { v[i] = d; return; }

  // query and change the MVector's size
  size_type size(void) const { return v.size(); }
  void resize(const size_type sz) { v.resize(sz); return; }

  // Form a new MVector by adding two MVectors.
  // Ex: (3 4 5.4 -2.3) + (0 -1.2 12 0) = (3 2.8 17.4 -2.3)
  // Assume the two MVectors have the same length.
  // You MUST use an STL function, e.g., sort, for_each.

  // ADD SOMETHING HERE

  // Increase the current MVector by the contents of another MVector.
  // Ex: If v = (3 4 5.4 -2.3) and w = (0 -1.2 12 0), then after
  // v += w, v = (3 2.8 17.4 -2.3).

  // ADD SOMETHING HERE

  // Form a new MVector by subtracting two MVectors.
  // Ex: (3 4 5.4 -2.3) - (0 -1.2 12 0) = (3 5.2 -6.6 -2.3)
  // Assume the two MVectors have the same length.
  // You MUST use an STL function, e.g., sort, for_each.

  // ADD SOMETHING HERE

  // Compute the dot product of two MVectors.
  // Ex: (2 3) * (1 4) = 2*1 + 3*4 = 14.
  // Assume the two MVectors have the same length.
  // Hint: Use an STL function.

  // ADD SOMETHING HERE

  // Scale an MVector.  I.e., multiply each vector component by a value.
  // Ex: 2 * (2 3) = (4 6).
  // You MUST use a while or for loop and iterators.

  // ADD SOMETHING HERE

  // Scale an MVector in place.  I.e., multiply each vector component
  // by a value, modifying the current MVector.
  // Ex: If v = (3 4 5.4 -2.3), then after v *= 2,
  // v = (6 8 10.8 -4.6).

  // ADD SOMETHING HERE

  // Compare two MVectors for equality, inequality. 
  // (1 3 2) == (1 3 2) should evaluate to "true", (1 3 2) == (0 0 0)
  // to "false", and (1 3 2) == (1 3) to "false".  (1 3 2) != (1 3 2)
  // should evaluate to "false", etc.

  // ADD SOMETHING HERE

  // input and output
  friend istream& operator>>(istream& in, MVector & mv) {
    // When doing input, do not change the given parameter until you
    // are sure the function will be successful.  For this particular
    // function, it does not really matter. :(
    MVector answer;
    double temp;
    while (in >> temp)
      answer.v.push_back(temp);
    mv.v.clear();
    mv = answer;
    return in;
  }

  // Write a function permitting an MVector to be output using the <<
  // operator.

  // ADD SOMETHING HERE

private:
  // We implement MVectors using STL vector<double>.
  vector<double> v;

  // ADD SOMETHING HERE, IF NEEDED
};