stoichiometricSubspace -- Computes the stoichiometric space of a Reaction Network.

i1 : N = reactionNetwork "A <--> B"

o1 = A-->B
     B-->A

o1 : ReactionNetwork

i2 : S = stoichiometricSubspace N

o2 = | -1 |
     | 1  |

              2       1
o2 : Matrix ZZ  <-- ZZ

i3 : N = oneSiteModificationA()

o3 = S_0+E-->X
     X-->S_0+E
     X-->E+S_1
     S_1+F-->Y
     Y-->S_1+F
     Y-->S_0+F

o3 : ReactionNetwork

i4 : S = stoichiometricSubspace N

o4 = | -1 -1 -1 |
     | -1 0  0  |
     | 1  0  0  |
     | 0  1  0  |
     | 0  0  -1 |
     | 0  0  1  |

              6       3
o4 : Matrix ZZ  <-- ZZ