acm-code-snippets/Linear Algebra.h at master · foreshadow/acm-code-snippets · GitHub

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namespace Infinity
{
namespace LinearAlgebra
{
class Vector
{
    typedef long double Real;

public:
    Real x;
    Real y;

    Vector(Real x, Real y) : x(x), y(y)
    {}

    Real length() const
    { return sqrtl(x * x + y * y); }

    Vector unit() const
    { return Vector(x / length(), y / length()); }

    Vector transpose() const
    { return Vector(y, x); }

    Vector left() const
    { return Vector(-y, x); }

    Vector right() const
    { return Vector(y, -x); }

    Vector operator -() const
    { return Vector(-x, -y); }

    Vector operator +(const Vector &v) const
    { return Vector(x + v.x, y + v.y); }

    Vector operator -(const Vector &v) const
    { return *this + -v; }

    Vector operator *(Real r) const
    { return Vector(x * r, y * r); }

    Vector operator /(Real r) const
    { assert(r != 0); return *this * (1 / r); }

    Real dot(const Vector &v) const
    { return x * v.x + y * v.y; }

    Real cross(const Vector &v) const
    { return x * v.y - y * v.x; }

    friend ostream &operator <<(ostream &os, const Vector& v)
    { return os << v.x << " " << v.y; }
};
} // namespace Infinity::LinearAlgebra
} // namespace Infinity