EXIT CONDITIONS AND CONTINUATION CALLS

The main task of DDAPLUS is to compute the state vector u (and the sensitivity matrix W if requested) at the next output point. The status of the solution upon return to the calling program is described by the parameter Idid, whose possible values are explained below. 

The initial UPRIME and h are ready at t = to, along with U updated from to- whenever algebraic equations are present. This is the normal return when DDAPLUS is called with tout=t. To commence integration, MAIN must call DDAPLUS again with tout moved from t in the direction indicated by the sign of h in Rwork(3). 

A successful integration step partway to tout is being reported under the option Info(3)=l. 

The integration has proceeded successfully across tout. The values of U and UPRIME (including sensitivity functions when requested) have been computed at tout by interpolation. If you want to continue the integration, MAIN must define a new tout and call the code again. You cannot change the direction of integration without restarting. 

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