anchor.diff:  
   !<##### 2 stages, SSP, 2nd order
   !< This scheme is an optmial SSP(2, 2) without low-storage algorithm. See *High Order Strong Stability Preserving Time
  -!< Discretizations*, Gottlieb, S., Ketcheson, D. I., Ketcheson, D., Journal of Scientific Computing, vol. 38, N. 3, 2009,
  +!< Discretizations*, Gottlieb, S., Ketcheson, D. I., Shu, C.W., Journal of Scientific Computing, vol. 38, N. 3, 2009,
   !< pp. 251-289.
   !< $$\beta = \left[ {\begin{array}{*{20}{c}} \frac{1}{2}&\frac{1}{2} \end{array}} \right]$$
   !< $$\alpha = \left[ {\begin{array}{*{20}{c}} 0&0\\ 1&0 \end{array}} \right]$$
  
positive.code: 
  !<##### 5 stages, SSP, 4th order
  !< This scheme is an optmial SSP(5, 4) without low-storage algorithm. See *High Order Strong Stability Preserving Time
  !< Discretizations*, Gottlieb, S., Ketcheson, D. I., Ketcheson, D., Journal of Scientific Computing, vol. 38, N. 3, 2009,
  !< pp. 251-289.
  !< $$\beta = \left[ {\begin{array}{*{20}{c}} 0.14681187618661&0.24848290924556&0.10425883036650&0.27443890091960&
  !< 0.22600748319395 \end{array}} \right]$$
  
negative.code: 
  !<##### 3 stages, SSP, 3rd order
  !< This scheme is an optmial SSP(3, 3) without low-storage algorithm. See *High Order Strong Stability Preserving Time
  !< Discretizations*, Gottlieb, S., Ketcheson, D. I., Shu, C.W., Journal of Scientific Computing, vol. 38, N. 3, 2009,
  !< pp. 251-289.
  !< $$\beta = \left[ {\begin{array}{*{20}{c}} \frac{1}{6}&\frac{1}{6}&\frac{1}{3}  \end{array}} \right]$$
  !< $$\alpha = \left[ {\begin{array}{*{20}{c}} 0&0&0\\ 1&0&0\\ \frac{1}{4}&\frac{1}{4}&0 \end{array}} \right]$$
  