## Solver Pane

The **Solver** pane includes parameters for configuring the
solver for a model. A solver computes the states for a dynamic system for each
simulation time step over the specified time span for the simulation. The
**Solver** pane also includes the parameters you use
to configure the simulation start and stop times that define the time span.

Once the model compiles, the Solver Information tooltip displays:

The compiled solver name

The step size, specified using the

**Max step size**parameter or the**Fixed-step size (fundamental sample time)**parameter.

Once the model compiles, the status bar displays the solver used for compiling and a carat (^) when:

The software selects a different solver during compilation.

You set the step size to

`auto`

. The Solver Information tooltip displays the step size that the software calculated.

When configuring the solver, consider that:

Simulation time is not the same as clock time. For example, running a simulation for 10 seconds usually does not take 10 seconds. Total simulation time depends on factors such as model complexity, solver step sizes, and computer speed.

Code generation requires selecting a fixed-step solver.

Selecting a variable-step solver can significantly shorten the time required to simulate models in which states change rapidly or contain discontinuities.

Parameter | Description |
---|---|

Specify the start time for the simulation or generated code as a double-precision value, scaled to seconds. | |

Specify the stop time for the simulation or generated code as a double-precision value, scaled to seconds. | |

Select the type of solver you want to use to simulate your model. | |

Select the solver you want to use to compute the states of the model during simulation or code generation. | |

Specify the largest time step that the solver can take. | |

Specify the integration order of the
`odeN` solver | |

Specify the size of the first time step that the solver takes. | |

Specify the smallest time step that the solver can take. | |

Specify the largest acceptable solver error, relative to the size of each state during each time step. If the relative error exceeds this tolerance, the solver reduces the time step size. | |

Specify the largest acceptable solver error, as the value of the measured state approaches zero. If the absolute error exceeds this tolerance, the solver reduces the time step size. | |

At each time step use derivative information to improve integration accuracy. | |

Select the order of the numerical
differentiation formulas (NDFs) used in the
| |

Select how the solver behaves during a reset, such as when it detects a zero crossing. | |

Specify the maximum number of consecutive minimum step size violations allowed during simulation. | |

Specify the method to compute the Jacobian matrix for an implicit solver. | |

Fine-tune the | |

Specify whether Simulink | |

Specify whether Simulink software automatically inserts hidden Rate Transition blocks between blocks that have different sample rates to ensure: the integrity of data transfers between tasks; and optional determinism of data transfers for periodic tasks. | |

Control whether the Rate Transition block
parameter | |

Specify whether the real-time system targeted by the model assigns higher or lower priority values to higher priority tasks when implementing asynchronous data transfers. | |

Enables zero-crossing detection during model simulation. For most models, this speeds up simulation by enabling the solver to take larger time steps. | |

Specify a tolerance factor that controls how closely zero-crossing events must occur to be considered consecutive. | |

Specify the number of consecutive zero crossings that can occur before Simulink software displays a warning or an error. | |

Specifies the algorithm to detect zero crossings when a variable-step solver is used. | |

Specifies the deadband region used during the detection of zero crossings. Signals falling within this region are defined as having crossed through zero. | |

Select constraints on the sample times defined by this model. If the model does not satisfy the specified constraints during simulation, Simulink software displays an error message. | |

Specify the step size used by the selected fixed-step solver. | |

Specify and assign priorities to the sample times that this model implements. | |

Select the extrapolation order used by the
| |

Specify the number of Newton's method
iterations used by the | |

Enable concurrent tasking behavior for model. | |

Enable automatic absolute tolerance adaptation | |

Enable Branched Input Multiple Outputs in rate-based models | |

Enable zero-crossing detection with fixed step | |

Specify maximum number of bracketing iterations performed when locating a zero crossing | |

Specify the maximum number of zero-crossings to locate in one fixed step |

These configuration parameters are in the **Advanced parameters**
section.

Parameter | Description |
---|---|

Removes the coupling between continuous and discrete rates. | |

Minimizes the impact of zero-crossings on the integration of continuous states. |