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Hold information about user-defined unit prefix


The UnitPrefix object contains information about user-defined unit prefixes. Use the object property Exponent to specify the exponent of your unit prefix.

Use dot notation to query the object properties or change properties that are not read-only. You can also use the get and set commands. findUsages lets you find out how a unit prefix is used in the built-in and custom libraries.

The SimBiology Model Builder app also enables you to change unit prefixes present in the libraries. For more information, see SimBiology Model Component Libraries.


Create a UnitPrefix object using sbiounitprefix and add the object to the library using sbioaddtolibrary.


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Exponent value of a unit prefix, specified as a nonnegative integer.

The property defines the numerical (exponent) value of the unit prefix. You can use the unit prefix in conjunction with any built-in or user-defined units. For example, you can define a unit prefix object petaPrefix with the Exponent property value set to 15.

Data Types: double

UnitPrefix object name, specified as a character vector or string.

For details on requirements and recommendations for naming SimBiology® components, see Guidelines for Naming Model Components.

Data Types: char | string

Additional information that you can add for UnitPrefix, specified as a character vector or string.

Data Types: char | string

This property is read-only.

Parent object, specified as [] or root object. The default property value is [] until you add the UnitPrefix object to the library. Then the value becomes a root object upon addition to the library.

The object label, specified as a character vector or string.


Use this property to group objects and then use sbioselect to retrieve. For example, use the Tag property of reaction objects to group synthesis or degradation reactions. You can then retrieve all synthesis reactions using sbioselect. Similarly, for species objects you can enter and store classification information, for example, membrane protein, transcription factor, enzyme classifications, or whether a species is an independent variable. You can also enter the full form of the name of the species.

Data Types: char | string

This property is read-only.

Object type, specified as 'unitprefix'. When you create a SimBiology object, the value of Type is automatically defined.

Data Types: char

Data to associate with the object, specified as a numeric scalar, vector, string, or any other MATLAB data type.

The object does not use this data directly, but you can access it using dot notation or get.

Object Functions

deleteDelete SimBiology object
displayDisplay summary of SimBiology object
findUsagesFind out how a unit or unit prefix is used
getGet SimBiology object properties
renameRename SimBiology model component and update expressions
setSet SimBiology object properties


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Create a unit prefix peta with the exponent value of 15.

petaPrefix = sbiounitprefix("peta",15);

Add the unit prefix to the library.


Check the library of unit prefixes. Note that peta has been added as a user-defined unit prefix.

ans = 
   SimBiology Unit Prefix Array

   Index:    Library:       Name:    Exponent:
   1         BuiltIn        centi    -2       
   2         BuiltIn        deci     -1       
   3         BuiltIn        deka     1        
   4         BuiltIn        femto    -15      
   5         BuiltIn        giga     9        
   6         BuiltIn        hecto    2        
   7         BuiltIn        kilo     3        
   8         BuiltIn        mega     6        
   9         BuiltIn        micro    -6       
   10        BuiltIn        milli    -3       
   11        BuiltIn        nano     -9       
   12        UserDefined    peta     15       
   13        BuiltIn        pico     -12      
   14        BuiltIn        tera     12       

Alternatively, you can use sbiowhos or the root object.

sbiowhos -userdefined -unitprefix
   SimBiology UserDefined Unit Prefixes
   Index:  Name:           Multiplier:              
   1       peta            1000000000000000         
rootObj = sbioroot;
ans = 
   SimBiology Unit Prefix Array

   Index:    Library:       Name:    Exponent:
   1         UserDefined    peta     15       

Version History

Introduced in R2008a