```ruby
#
# Array クラス拡張メソッド
#
class Array

  def to_v
    Vec::new self
  end

  def trans(t)
    t.move_point self
  end

  def trans!(t)
    r = t.move_point self
    x = r.x, y = r.y, z = r.z
  end

  def x
    val = (self[0] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def y
    val = (self[1] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def z
    val = (self[2] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def x=(val); self[0] = val end
  def y=(val); self[1] = val end
  def z=(val); self[2] = val end

end

```

Add dist method to Array.
user
```ruby
#
# Array クラス拡張メソッド
#
class Array

  def to_v
    Vec::new self
  end

  def dist(other)
    (self.to_v - other.to_v).magnitude
  end

  def trans(t)
    t.move_point self
  end

  def trans!(t)
    r = t.move_point self
    x = r.x, y = r.y, z = r.z
  end

  def x
    val = (self[0] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def y
    val = (self[1] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def z
    val = (self[2] ||= 0.0)
    if val.is_a?(Float)
      val
    elsif val.is_a?(Numeric)
      val.to_f
    else
      0.0
    end
  end

  def x=(val); self[0] = val end
  def y=(val); self[1] = val end
  def z=(val); self[2] = val end

end

```
assistant