## ODE solver

During time transitions, the values of the continuous variables and their derivatives change. These changes are calculated using an ODE integrator. As soon as a guard for an event becomes enabled, time should no longer progress. To calculate whether (and when) guards change value, a root finding algorithm is used. Software to solve ODEs, through integration and root finding, are often called ODE solvers. The CIF simulator uses the The Apache Commons Mathematics Library. This library contains ODE solvers, with several different integrators and root finding algorithms.

Debug information about what the ODE solver calculates, and for what time points, can be enabled using the Debug output option. See the Debug console output page for more information.

Basic topics

- The basics of numeric integration

- The basics of numeric root finding

- Problems with root finding (and missed guards/events)

- Fixed output step size

Advanced topics

- Simulation end time and maximum delay

- ODE solver integrator options

- ODE solver root finder options