UnitConversion - Perform unit conversion

Description

The UnitConversion property specifies whether to perform unit conversion for the model before simulation. It is a property of the CompileOptions object. CompileOptions holds the model's compile time options and is the object property of the configset object.

When UnitConversion is set to true, the SimBiology software converts the matching physical quantities to one consistent unit system in order to resolve them. This conversion is in preparation for correct simulation, but species amounts are returned in the user-specified units.

For example, consider a reaction a + b —> c. Using mass action kinetics the reaction rate is defined as a*b*k where k is the rate constant of the reaction. If you specify that initial amounts of a and b are 0.01M and 0.005M respectively, then units of k are 1/(M*second). If you specify k with another equivalent unit definition, for example, 1/((molecules/liter)*second), UnitConversion occurs after DimensionalAnalysis.

Unit conversion requires dimensional analysis. If DimensionalAnalysis is off, and you turn UnitConversion on, then DimensionalAnalysis is turned on automatically. If UnitConversion is on and you turn off DimensionalAnalysis, then UnitConversion is turned off automatically.

If UnitConversion fails, then you see an error when you simulate (sbiosimulate).

If UnitConversion is set to false, the simulation uses the given object values.

Unit conversion involving temperature supports Celsius as the temperature unit. Avoid using mixed temperature units as you might get an error.

Characteristics

Applies to	Object: CompileOptions (in configset object)
Data type	boolean
Data values	true or false. Default value is false.
Access	Read/write

Examples

This example shows how to retrieve and set unitconversion from the default true to false in the default configuration set in a model object.

1. Import a model.

   modelObj = sbmlimport('oscillator')

   SimBiology Model - Oscillator 
   
      Model Components:
        Models:            0
        Parameters:        0
        Reactions:         42
        Rules:             0
        Species:           23
   

2. Retrieve the configset object of the model object.

   configsetObj = getconfigset(modelObj)
   
    Configuration Settings - default (active)
        SolverType:           ode15s
        StopTime:             10.000000
   
      SolverOptions:
        AbsoluteTolerance:    1.000000e-006
        RelativeTolerance:    1.000000e-003
   
      RuntimeOptions:
        StatesToLog:          all
   
      CompileOptions:
        UnitConversion:       false
        DimensionalAnalysis:  true

3. Retrieve the CompileOptions object.

   optionsObj = get(configsetObj,'CompileOptions')
   
   Compile Settings:
   
        UnitConversion:       false
        DimensionalAnalysis:  true

4. Assign a value of false to UnitConversion.

    set(optionsObj,'UnitConversion', true)

See Also

get, getconfigset, sbiosimulate, set

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