Refine factor

Option to produce additional output values between simulation time steps

Model Configuration Pane: Data Import/Export

Description

Specify the amount of additional output values for the variable-step solver to produce. A refine factor of 1 specifies that the simulation produce the same number of output values. A refine factor of 2 specifies that the simulation produce twice the number of output values. The solver does not produce these values by taking additional major time steps.

This parameter is supported only for simulations that use a variable-step solver. In simulations that use a fixed-step solver, this parameter is ignored.

This parameter is also ignored in simulations of purely discrete models, which contain no continuous states.

The software always simulates purely discrete models using the discrete solver for the selected solver type, regardless of the value you specify for the Solver parameter.

Dependencies

To enable this parameter, set Output options to Refine output.

Settings

1 (default) | positive integer greater than zero

By default, the refine factor is 1, and the simulation does not produce additional output values. When you specify a refine factor of 2, the simulation produces approximately twice the number of output values by calculating an additional output value midway between each major time step.

Recommended Settings

The table summarizes recommended values for this parameter based on considerations related to code generation.

Application	Setting
Debugging	No impact
Traceability	No impact
Efficiency	No recommendation
Safety precaution	No recommendation

Programmatic Use

Parameter: Refine

Type: string | character vector

Value: positive integer greater than zero

Default: '1'

Version History

Introduced before R2006a

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R2022a: Refine factor parameter ignored for purely discrete models

Simulations of purely discrete models that use variable-step solvers no longer log redundant data values when you specify a value for the Refine factor parameter.

Continuous state and continuous state derivative values can change at any time in simulation. Solvers compute continuous dynamics based on continuous states and continuous state derivatives in the model. In variable-step simulations, solvers propagate simulation time and ensure the accuracy of simulation results by checking whether taking a given step satisfies tolerance requirements for continuous state values.

By contrast, discrete state values change only at simulation time hits that correspond to the discrete sample time associated with the state. When a model contains no states or only discrete states, specifying a refine factor for logged data does not provide additional information about the logged signals or the simulation because, by definition, the system dynamics cannot change between the major time steps of the simulation.