In the case in which the problem to be solve is nonlinear, the user can choose a scheme with nonconstant stepsize. In this case he must specify the number of steps for which the stepsize must remain constant (this number will effect the method stability). Since a general theory for a variable stepsize A-method has not been elaborated until now, the decision of the number of steps for which the stepsize is constant hangs on the user. If this number will be small relative the estimated number of steps, it is possible that the computation process will be stopped because of some instabilities of the numerical method. The initial stepsize will be h₀. New estimations of the computation time and the number of steps when changing the stepsize are not provided in this version of EpODE. The user cannot influence the new stepsize value: this will be computed using eq, more exactly the half-value of the right side - the value T correspond in this case with the remaining integration interval.

Example for the method DIRK4 applied to the system B1.