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
Start time	Specify the start time for the simulation or generated code as a double-precision value, scaled to seconds.
Stop time	Specify the stop time for the simulation or generated code as a double-precision value, scaled to seconds.
Type	Select the type of solver you want to use to simulate your model.
Solver	Select the solver you want to use to compute the states of the model during simulation or code generation.
Max step size	Specify the largest time step that the solver can take.
Integration method	Specify the integration order of the odeN solver
Initial step size	Specify the size of the first time step that the solver takes.
Min step size	Specify the smallest time step that the solver can take.
Relative tolerance	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.
Absolute tolerance	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.
Shape preservation	At each time step use derivative information to improve integration accuracy.
Maximum order	Select the order of the numerical differentiation formulas (NDFs) used in the ode15s solver.
Solver reset method	Select how the solver behaves during a reset, such as when it detects a zero crossing.
Number of consecutive min steps	Specify the maximum number of consecutive minimum step size violations allowed during simulation.
Solver Jacobian Method	Specify the method to compute the Jacobian matrix for an implicit solver.
Daessc mode	Fine-tune the daessc solver performance.
Treat each discrete rate as a separate task	Specify whether Simulink® executes blocks with periodic sample times individually or in groups.
Automatically handle rate transition for data transfer	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.
Deterministic data transfer	Control whether the Rate Transition block parameter Ensure deterministic data transfer (maximum delay) is set for auto-inserted Rate Transition blocks.
Higher priority value indicates higher task priority	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.
Zero-crossing control	Enables zero-crossing detection during model simulation. For most models, this speeds up simulation by enabling the solver to take larger time steps.
Time tolerance	Specify a tolerance factor that controls how closely zero-crossing events must occur to be considered consecutive.
Number of consecutive zero crossings	Specify the number of consecutive zero crossings that can occur before Simulink software displays a warning or an error.
Algorithm	Specifies the algorithm to detect zero crossings when a variable-step solver is used.
Signal threshold	Specifies the deadband region used during the detection of zero crossings. Signals falling within this region are defined as having crossed through zero.
Periodic sample time constraint	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.
Fixed-step size (fundamental sample time)	Specify the step size used by the selected fixed-step solver.
Sample time properties	Specify and assign priorities to the sample times that this model implements.
Extrapolation order	Select the extrapolation order used by the ode14x solver to compute a model's states at the next time step from the states at the current time step.
Number of Newton's iterations	Specify the number of Newton's method iterations used by the ode14x solver to compute a model's states at the next time step from the states at the current time step.
Allow tasks to execute concurrently on target	Enable concurrent tasking behavior for model.
Auto scale absolute tolerance	Enable automatic absolute tolerance adaptation
Allow multiple tasks to access inputs and outputs	Enable Branched Input Multiple Outputs in rate-based models
Enable zero-crossing detection for fixed-step simulation	Enable zero-crossing detection with fixed step
Maximum number of bracketing iterations	Specify maximum number of bracketing iterations performed when locating a zero crossing
Maximum number of zero-crossings per step	Specify the maximum number of zero-crossings to locate in one fixed step

These configuration parameters are in the Advanced parameters section.

Parameter	Description
Enable decoupled continuous integration	Removes the coupling between continuous and discrete rates.
Enable minimal zero-crossing impact integration	Minimizes the impact of zero-crossings on the integration of continuous states.

Related Topics

• Solver Selection Criteria