anchor.diff:  
   Ray defines a line that starts at a point *A* and continues in a direction through *B* into infinity.
   
  -This Ray is used extensively in jME for <<jme3/picking#,Picking>>. A Ray is cast from a point in screen space into the scene. Intersections are found and returned. To create a ray supply the object with two points, where the first point is the origin.
  +This Ray is used extensively in jME for <<jme3/beginner/hello_picking,Picking>>. A Ray is cast from a point in screen space into the scene. Intersections are found and returned. To create a ray supply the object with two points, where the first point is the origin.
   
   
   === Example 1 - Create a Ray That Represents Where the Camera is Looking
  
positive.code: 
  ===== Trig Functions
  
  * cos and acos - provide link:http://en.wikipedia.org/wiki/cosine[cosine] and link:http://en.wikipedia.org/wiki/arc cosine[arc cosine] values (make use of the look-up table if `USE_FAST_TRIG` is true)
  * sin and asin - provide link:http://en.wikipedia.org/wiki/sine[sine] and link:http://en.wikipedia.org/wiki/arc sine[arc sine] values (make use of the look-up table if `USE_FAST_TRIG` is true)
  * tan and atan - provide link:http://en.wikipedia.org/wiki/tangent[tangent] and link:http://en.wikipedia.org/wiki/arc tangent[arc tangent] values
  
  
  ===== Numerical Methods
  
  * ceil - provides the ceiling (smallest value that is greater than or equal to a given value and an integer)of a value.
  * floor - provides the floor (largest value that is less than or equal to a given value and an integer) of a value.
  * exp - provides the link:http://en.wikipedia.org/wiki/euler number[euler number] (e) raised to the provided value.
  * sqr - provides the square of a value (i.e. value * value).
  * pow - provides the first given number raised to the second.
  * isPowerOfTwo - provides a boolean if a value is a power of two or not (e.g. 32, 64, 4).
  * abs - provides the link:http://en.wikipedia.org/wiki/absolute value[absolute value] of a given number.
  * sign - provides the sign of a value (1 if positive, -1 if negative, 0 if 0).
  * log - provides the link:http://en.wikipedia.org/wiki/natural logarithm[natural logarithm] of a value.
  * sqrt - provides the link:http://en.wikipedia.org/wiki/square root[square root] of a value.
  * invSqrt - provides the inverse link:http://en.wikipedia.org/wiki/square root[square root] of a value (1 / sqrt(value).
  
  
  ===== Linear Algebra
  
  * LERP - calculate the link:http://en.wikipedia.org/wiki/Linear interpolation[linear interpolation] of two points given a time between 0 and 1.
  * determinant - calculates the link:http://en.wikipedia.org/wiki/determinant[determinant] of a 4x4 matrix.
  
  
  
negative.code: 
  === jME Usage
  
  Rectangle is a straight forward data class that simply maintains values that defines a Rectangle in 3D space. One interesting use is the `random` method that will create a random point on the Rectangle. The <<jme3/advanced/effects_overview#,Particle System>> makes use of this to define an area that generates <<jme3/advanced/particle_emitters#,Particles>>.
  
  
  === Example 1 : Define a Rectangle and Get a Point From It
  