Find transition firing order
tran = firingorder(forward,backward,initmark,mark)
This function is used to find transition firing order to reach state where that state covers mark. Variable mark is become input of this function. Besides that this function needs forward incidence, backward incidence and initial state of Petri net. The output of this function denoted by tran. Variable tran is a matrix where its column represents one transition firing order from top to bottom. Number of column shows number of different firing order. Number of rows represents number of transitions that fired.