fixdt

Create Simulink.NumericType object describing a fixed-point or floating-point data type

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Syntax

a = fixdt(Signed,WordLength)

a = fixdt(Signed,WordLength,FractionLength)

a = fixdt(Signed,WordLength,TotalSlope,Bias)

a = fixdt(Signed,WordLength,SlopeAdjustmentFactor,FixedExponent,Bias)

a = fixdt(DataTypeNameString)

a = fixdt(___,'DataTypeOverride','Off')

[a,IsScaledDouble] = fixdt(___)

Description

a = fixdt(Signed,WordLength) returns a Simulink.NumericType object that describes a fixed-point data type with the specified signedness and word length, and unspecified scaling.

example

a = fixdt(Signed,WordLength,FractionLength) returns a Simulink.NumericType object that describes a fixed-point data type with binary point scaling.

example

a = fixdt(Signed,WordLength,TotalSlope,Bias) returns a Simulink.NumericType object that describes a fixed-point data type with slope and bias scaling.

example

a = fixdt(Signed,WordLength,SlopeAdjustmentFactor,FixedExponent,Bias) returns a Simulink.NumericType object that describes a fixed-point data type with slope and bias scaling.

example

a = fixdt(DataTypeNameString) returns a Simulink.NumericType object that describes an integer, fixed-point, or floating-point data type specified by the name of a data type.

example

a = fixdt(___,'DataTypeOverride','Off') returns a Simulink.NumericType object with its DataTypeOverride parameter set to Off. The default value for this property is Inherit. You can specify the DataTypeOverride parameter after any combination of other input parameters.

example

[a,IsScaledDouble] = fixdt(___) returns a Simulink.NumericType object that describes a fixed-point or floating-point data type and a flag that indicates whether the specified data type is of a scaled double data type.

example

Examples

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Create a `Simulink.NumericType` Object with Unspecified Scaling

Open Live Script

Create a signed Simulink.NumericType object with a word length of 16 bits and unspecified scaling.

a = fixdt(1,16)

a = 
  NumericType with properties:

    DataTypeMode: 'Fixed-point: unspecified scaling'
      Signedness: 'Signed'
      WordLength: 16
         IsAlias: 0
       DataScope: 'Auto'
      HeaderFile: ''
     Description: ''

Create a `Simulink.NumericType` Object with Binary Point Scaling

Open Live Script

Create a Simulink.NumericType object that describes a signed fixed-point data type with a word length of 16 bits and fraction length of 2 bits.

a = fixdt(1,16,2)

a = 
  NumericType with properties:

      DataTypeMode: 'Fixed-point: binary point scaling'
        Signedness: 'Signed'
        WordLength: 16
    FractionLength: 2
           IsAlias: 0
         DataScope: 'Auto'
        HeaderFile: ''
       Description: ''

Create a `Simulink.NumericType` Object with Slope and Bias Scaling

Open Live Script

The real-world value of a slope bias scaled number is represented by:

$real world value = (slope \times integer) + bias$

Create a Simulink.NumericType object that describes a signed fixed-point data type with a word length of 16 bits, slope of 2^-2, and bias of 4.

a = fixdt(1,16,2^-2,4)

a = 
  NumericType with properties:

    DataTypeMode: 'Fixed-point: slope and bias scaling'
      Signedness: 'Signed'
      WordLength: 16
           Slope: 0.2500
            Bias: 4
         IsAlias: 0
       DataScope: 'Auto'
      HeaderFile: ''
     Description: ''

Alternatively, the slope can by represented by:

$slope = slopeadjustmentfactor \times 2^{fixedexponent}$

a = fixdt(1,16,1,-2,4)

a = 
  NumericType with properties:

    DataTypeMode: 'Fixed-point: slope and bias scaling'
      Signedness: 'Signed'
      WordLength: 16
           Slope: 0.2500
            Bias: 4
         IsAlias: 0
       DataScope: 'Auto'
      HeaderFile: ''
     Description: ''

The DataTypeMode property of the Simulink.NumericType object, a, is slope and bias scaling.

Create a `Simulink.NumericType` Object Using a Data Type Name

Open Live Script

Use a data type name to create a Simulink.NumericType object that describes an 8-bit, unsigned, fixed-point data type and return a flag that indicates whether the object is of a scaled double data type.

[a,IsScaledDouble] = fixdt('ufix8')

a = 
  NumericType with properties:

      DataTypeMode: 'Fixed-point: binary point scaling'
        Signedness: 'Unsigned'
        WordLength: 8
    FractionLength: 0
           IsAlias: 0
         DataScope: 'Auto'
        HeaderFile: ''
       Description: ''

IsScaledDouble = logical
   0

The IsScaledDouble output returns 0, which indicates that the data type of a is not a scaled double data type.

Create a `Simulink.NumericType` Object with `DataTypeOverride` Set to `Off`

Open Live Script

Create a Simulink.NumericType object with its DataTypeOverride property set to Off.

a = fixdt(0,8,2,'DataTypeOverride','Off')

a = 
  NumericType with properties:

        DataTypeMode: 'Fixed-point: binary point scaling'
          Signedness: 'Unsigned'
          WordLength: 8
      FractionLength: 2
    DataTypeOverride: 'Off'
             IsAlias: 0
           DataScope: 'Auto'
          HeaderFile: ''
         Description: ''

Input Arguments

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`Signed` — Signedness
`true` or `1` | `false` or `0`

Signedness of the Simulink.NumericType object, specified as a numeric or logical 1 (true) or 0 (false). A value of 1, or true, indicates a signed data type. A value of 0, or false, indicates an unsigned data type.

Data Types: logical

`WordLength` — Word length
positive scalar

Word length, in bits, of the Simulink.NumericType object, specified as a positive scalar.

`FractionLength` — Fraction length
`0` (default) | scalar

Fraction length, in bits, of the Simulink.NumericType object, specified as a scalar.

FractionLength can be greater than WordLength. For more information, see Binary Point Interpretation (Fixed-Point Designer).

`TotalSlope` — Slope of the scaling
`1` (default) | scalar

Slope of the scaling, specified as a scalar.

The following equation represents the real-world value of a slope bias scaled number:

$r e a l w o r l d v a l u e = (s l o p e \times i n t e g e r) + b i a s$

`Bias` — Bias of the scaling
`0` (default) | scalar

Bias of the scaling, specified as a scalar.

The following equation represents the real-world value of a slope bias scaled number:

$r e a l w o r l d v a l u e = (s l o p e \times i n t e g e r) + b i a s$

`SlopeAdjustmentFactor` — Slope adjustment factor of slope and bias scaled number
`1` (default) | positive scalar

Slope adjustment factor of a slope bias scaled number, specified as a positive scalar.

The slope adjustment factor must be greater than or equal to 1 and less than 2. If you input a SlopeAdjustmentFactor outside this range, fixdt automatically applies a scaling normalization to the values of SlopeAdjustmentFactor and FixedExponent so that the revised slope adjustment factor is greater than or equal to 1 and less than 2, and maintains the value of the slope.

The following equation demonstrates the relationship between the slope, fixed exponent, and slope adjustment factor:

$s l o p e = s l o p e a d j u s t m e n t f a c t o r \times 2^{f i x e d e x p o n e n t}$

`FixedExponent` — Fixed exponent of slope and bias scaled number
`0` (default) | scalar

Fixed exponent of a slope bias scaled number, specified as a scalar.

The following equation demonstrates the relationship between the slope, fixed exponent, and slope adjustment factor:

$s l o p e = s l o p e a d j u s t m e n t f a c t o r \times 2^{f i x e d e x p o n e n t}$

`DataTypeNameString` — Data type name
character vector

Data type name, specified as a character vector.

The data type name can be either the name of a built-in Simulink^® data type or the name of a fixed-point data type that conforms to the naming convention for fixed-point names established by the Fixed-Point Designer™ product. For more information, see Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).

Data Types: char

Output Arguments

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`a` — Data type
`Simulink.NumericType` object

Data type, returned as a Simulink.NumericType object.

`IsScaledDouble` — Scaled double flag
logical

Scaled double flag, returned as a logical that indicates whether the specified data type name is the name of a scaled double data type.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

For the fixdt function, code is generated via the embedded.numerictype object. The Simulink.NumericType object is not supported for code generation.

HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

Version History

Introduced before R2006a

fixdt

Syntax

Description

Examples

Create a `Simulink.NumericType` Object with Unspecified Scaling

Create a `Simulink.NumericType` Object with Binary Point Scaling

Create a `Simulink.NumericType` Object with Slope and Bias Scaling

Create a `Simulink.NumericType` Object Using a Data Type Name

Create a `Simulink.NumericType` Object with `DataTypeOverride` Set to `Off`

Input Arguments

`Signed` — Signedness
`true` or `1` | `false` or `0`

`WordLength` — Word length
positive scalar

`FractionLength` — Fraction length
`0` (default) | scalar

`TotalSlope` — Slope of the scaling
`1` (default) | scalar

`Bias` — Bias of the scaling
`0` (default) | scalar

`SlopeAdjustmentFactor` — Slope adjustment factor of slope and bias scaled number
`1` (default) | positive scalar

`FixedExponent` — Fixed exponent of slope and bias scaled number
`0` (default) | scalar

`DataTypeNameString` — Data type name
character vector

Output Arguments

`a` — Data type
`Simulink.NumericType` object

`IsScaledDouble` — Scaled double flag
logical

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

Version History

See Also

Topics

fixdt

Syntax

Description

Examples

Create a Simulink.NumericType Object with Unspecified Scaling

Create a Simulink.NumericType Object with Binary Point Scaling

Create a Simulink.NumericType Object with Slope and Bias Scaling

Create a Simulink.NumericType Object Using a Data Type Name

Create a Simulink.NumericType Object with DataTypeOverride Set to Off

Input Arguments

Signed — Signedness true or 1 | false or 0

WordLength — Word length positive scalar

FractionLength — Fraction length 0 (default) | scalar

TotalSlope — Slope of the scaling 1 (default) | scalar

Bias — Bias of the scaling 0 (default) | scalar

SlopeAdjustmentFactor — Slope adjustment factor of slope and bias scaled number 1 (default) | positive scalar

FixedExponent — Fixed exponent of slope and bias scaled number 0 (default) | scalar

DataTypeNameString — Data type name character vector

Output Arguments

a — Data type Simulink.NumericType object

IsScaledDouble — Scaled double flag logical

Extended Capabilities

C/C++ Code Generation Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

Version History

See Also

Topics

Create a `Simulink.NumericType` Object with Unspecified Scaling

Create a `Simulink.NumericType` Object with Binary Point Scaling

Create a `Simulink.NumericType` Object with Slope and Bias Scaling

Create a `Simulink.NumericType` Object Using a Data Type Name

Create a `Simulink.NumericType` Object with `DataTypeOverride` Set to `Off`

`Signed` — Signedness
`true` or `1` | `false` or `0`

`WordLength` — Word length
positive scalar

`FractionLength` — Fraction length
`0` (default) | scalar

`TotalSlope` — Slope of the scaling
`1` (default) | scalar

`Bias` — Bias of the scaling
`0` (default) | scalar

`SlopeAdjustmentFactor` — Slope adjustment factor of slope and bias scaled number
`1` (default) | positive scalar

`FixedExponent` — Fixed exponent of slope and bias scaled number
`0` (default) | scalar

`DataTypeNameString` — Data type name
character vector

`a` — Data type
`Simulink.NumericType` object

`IsScaledDouble` — Scaled double flag
logical

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.