Simpath-spread

v4 is the newst version.
1.The forward_algorithm is not so hard to use the stack, it's just because the error of mine
2.The simpath_spread runs time in csie workstation as listed below:
  eta        time/s            S                 Value
  0           180s             '0'                1.*
  0.1         1.*s             '0'                24.780645074308694
  0.01        1.*s             '0'                31.54879969958534
  0.001       1.*s             '0'                29.78273681687069
  0.0001      1.*s             '0'                28.76543230663251
  0.1         1.*s             '0','1'            26.120708074308702
  0.001       1.*s             '0','1'            30.97605754115106
  0.01        1.*s             '0','1','2','3','100','102','103'            41.7717804074
  0.001       1.*s             '0','1','2','3','100','102','103'            41.8471153943
  3 The program is tested for more times,so it may be right in a proper use, but the result is a litter absurd,talk about it more tomorrow.