code: public Matrix4d rotationY(double ang) {
          double sin, cos;
          sin = Math.sin(ang);
          cos = Math.cosFromSin(sin, ang);
          if ((properties & PROPERTY_IDENTITY) == 0)
              this._identity();
          m00 = cos;
          m02 = -sin;
          m20 = sin;
          m22 = cos;
          properties = PROPERTY_AFFINE | PROPERTY_ORTHONORMAL;
          return this;
      }
docs: Set this matrix to a rotation transformation about the Y axis.
  <p>
  When used with a right-handed coordinate system, the produced rotation will rotate a vector
  counter-clockwise around the rotation axis, when viewing along the negative axis direction towards the origin.
  When used with a left-handed coordinate system, the rotation is clockwise.
  <p>
  Reference: <a href="http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations">http://en.wikipedia.org</a>
  
  @param ang
  the angle in radians
  @return this