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Parameter value units


The ValueUnits property indicates the unit definition of the Value property of a parameter object.

ValueUnits can be one of the built-in units. To get a list of the built-in units, use the sbioshowunits function. If ValueUnits changes from one unit definition to another, the Value does not automatically convert to the new units. The sbioconvertunits function does this conversion.

The ValueUnits property is identical to the Units property.


Applies toObject: species, compartment, parameter
Data typeCharacter vector
Data valuesUnit from units library. Default is '' (empty character vector). Note that the default value of an empty character vector means unspecified. Unspecified units are permitted during dimensional analysis, but not during unit conversion. (Use 'dimensionless' to specify dimensionless units.)


SimBiology® uses units including empty units in association with DimensionalAnalysis and UnitConversion features.

  • When DimensionalAnalysis and UnitConversion are both false, units are not used. However, SimBiology still performs a minimum level of dimensional analysis to decide whether a reaction rate is in dimensions of amount/time or concentration/time.

  • When DimensionalAnalysis is true and UnitConversion is false, units (if not empty) must have consistent dimensions so that SimBiology can perform dimensional analysis. However, the units are not converted.

  • When UnitConversion is set to true (which requires DimensionalAnalysis to be true), SimBiology performs a dimensional analysis and converts everything to consistent units. Hence, you must specify consistent units, and no units can be empty. If you have a dimensionless parameter, you must still set its unit to dimensionless.


Assign a parameter with a value to the model object.

  1. Create a model object, and then add a reaction object.

    modelObj = sbiomodel('my_model');
  2. Add a parameter with Value 0.5, and assign it to the model object (modelObj).

    parameterObj1 = addparameter(modelObj, 'K1', 0.5, 'ValueUnits', '1/second')

    MATLAB® returns:

    SimBiology Parameter Array
    Index:    Name:    Value:    ValueUnits:
     1         K1       0.5       1/second