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globalfimath

Configure global fimath and return handle object

Syntax

G = globalfimath
G = globalfimath('PropertyName1',PropertyValue1,...)
G = globalfimath(f)

Description

G = globalfimath returns a handle object to the global fimath. The global fimath has identical properties to a fimath object but applies globally.

G = globalfimath('PropertyName1',PropertyValue1,...) sets the global fimath using the named properties and their corresponding values. Properties that you do not specify in this syntax are automatically set to that of the current global fimath.

G = globalfimath(f) sets the properties of the global fimath to match those of the input fimath object f, and returns a handle object to it.

Unless, in a previous release, you used the saveglobalfimathpref function to save global fimath settings to your MATLAB® preferences, the global fimath properties you set with the globalfimath function apply only to your current MATLAB session. It is best practice to remove global fimath from the MATLAB preferences so that you start each MATLAB session using the default fimath settings. To remove the global fimath, use the removeglobalfimathpref function.

Modifying globalfimath

Use the globalfimath function to set, change, and reset the global fimath.

Create a fimath object and use it as the global fimath.

G = globalfimath('RoundMode','Floor','OverflowMode','Wrap')
 
G =
 

        RoundingMethod: Floor
        OverflowAction: Wrap
           ProductMode: FullPrecision
               SumMode: FullPrecision

Create another fimath object using the new default.

F1 = fimath
 
F1 =
 

        RoundingMethod: Floor
        OverflowAction: Wrap
           ProductMode: FullPrecision
               SumMode: FullPrecision

Create a fi object, A, associated with the global fimath.

A = fi(pi)
A = 

    3.1416

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 16
        FractionLength: 13

Now set the "SumMode" property of the global fimath to "KeepMSB" and retain all the other property values of the current global fimath.

G = globalfimath('SumMode','KeepMSB')
 
G =
 

        RoundingMethod: Floor
        OverflowAction: Wrap
           ProductMode: FullPrecision
               SumMode: KeepMSB
         SumWordLength: 32
         CastBeforeSum: true

Change the global fimath by directly interacting with the handle object G.

G.ProductMode = 'SpecifyPrecision'
 
G =
 

        RoundingMethod: Floor
        OverflowAction: Wrap
           ProductMode: SpecifyPrecision
     ProductWordLength: 32
 ProductFractionLength: 30
               SumMode: KeepMSB
         SumWordLength: 32
         CastBeforeSum: true

Reset the global fimath to the factory default by calling the reset method on G. This is equivalent to using the resetglobalfimath function.

reset(G);
G
 
G =
 

        RoundingMethod: Nearest
        OverflowAction: Saturate
           ProductMode: FullPrecision
               SumMode: FullPrecision

Tips

If you always use the same fimath settings and you are not sharing code with other people, using the globalfimath function is a quick, convenient method to configure these settings. However, if you share the code with other people or if you use the fiaccel function to accelerate the algorithm or you generate C code for your algorithm, consider the following alternatives.

GoalIssue Using globalfimathSolution

Share code

If you share code with someone who is using different global fimath settings, they might see different results.

Separate the fimath properties from your algorithm by using types tables. For more information, see Separate Data Type Definitions from Algorithm.

Accelerate your algorithm using fiaccel or generate C code from your MATLAB algorithm using codegen

You cannot use globalfimath within that algorithm. If you generate code with one globalfimath setting and run it with a different globalfimath setting, results might vary. For more information, see Specifying Default fimath Values for MEX Functions.

Use types tables in the algorithm from which you want to generate code. This insulates you from the global settings and makes the code portable. For more information, see Separate Data Type Definitions from Algorithm.

See Also

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