code: public Matrix4d setOrthoSymmetric(double width, double height, double zNear, double zFar) {
          return setOrthoSymmetric(width, height, zNear, zFar, false);
      }
docs: Set this matrix to be a symmetric orthographic projection transformation for a right-handed coordinate system
  using OpenGL's NDC z range of <code>[-1..+1]</code>.
  <p>
  This method is equivalent to calling {@link #setOrtho(double, double, double, double, double, double) setOrtho()} with
  <code>left=-width/2</code>, <code>right=+width/2</code>, <code>bottom=-height/2</code> and <code>top=+height/2</code>.
  <p>
  In order to apply the symmetric orthographic projection to an already existing transformation,
  use {@link #orthoSymmetric(double, double, double, double) orthoSymmetric()}.
  <p>
  Reference: <a href="http://www.songho.ca/opengl/gl_projectionmatrix.html#ortho">http://www.songho.ca</a>
  
  @see #orthoSymmetric(double, double, double, double)
  
  @param width
  the distance between the right and left frustum edges
  @param height
  the distance between the top and bottom frustum edges
  @param zNear
  near clipping plane distance
  @param zFar
  far clipping plane distance
  @return this