numerictype of Fixed-Point Objects

Valid Values for `numerictype` Object Properties

The numerictype object contains all the data type and scaling attributes of a fixed-point object. The numerictype object behaves like any MATLAB^® object, except that it only lets you set valid values for defined fields. The following table shows the possible settings of each field of the object.

Note

When you create a fi object, any unspecified field of the numerictype object reverts to its default value. Thus, if the DataTypeMode is set to unspecified scaling, it defaults to binary point scaling when the fi object is created. If the Signedness property of the numerictype object is set to Auto, it defaults to Signed when the fi object is created.

DataTypeMode	DataType	Scaling	Signedness	Word- Length	Fraction- Length	Slope	Bias
Fixed-point data types
`Fixed-point: binary point scaling`	`Fixed`	`BinaryPoint`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	Positive or negative integer	2^(-fraction length)	`0`
`Fixed-point: slope and bias scaling`	`Fixed`	`SlopeBias`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	`N/A`	Any floating- point number greater than zero	Any floating- point number
`Fixed-point: unspecified scaling`	`Fixed`	`Unspecified`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	`N/A`	`N/A`	`N/A`
Scaled double data types
`Scaled double: binary point scaling`	`ScaledDouble`	`BinaryPoint`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	Positive or negative integer	2^(-fraction length)	`0`
`Scaled double: slope and bias scaling`	`ScaledDouble`	`SlopeBias`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	`N/A`	Any floating- point number greater than zero	Any floating- point number
`Scaled double: unspecified scaling`	`ScaledDouble`	`Unspecified`	`Signed` `Unsigned` `Auto`	Positive integer from 1 to 65,535	`N/A`	`N/A`	`N/A`
Built-in data types
`Double`	`double`	`N/A`	`1` `true`	`64`	`0`	`1`	`0`
`Single`	`single`	`N/A`	`1` `true`	`32`	`0`	`1`	`0`
`Boolean`	`boolean`	`N/A`	`0` `false`	`1`	`0`	`1`	`0`

You cannot change the numerictype properties of a fi object after fi object creation.

Properties That Affect the Slope

The Slope field of the numerictype object is related to the SlopeAdjustmentFactor and FixedExponent properties by

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

The FixedExponent and FractionLength properties are related by

$f i x e d e x p o n e n t = - f r a c t i o n l e n g t h$

If you set the SlopeAdjustmentFactor, FixedExponent, or FractionLength property, the Slope field is modified.

Stored Integer Value and Real World Value

In binary point scaling the numerictype StoredIntegerValue and RealWorldValue properties are related according to

$r e a l - w o r l d v a l u e = s t o r e d i n t e g e r v a l u e \times 2^{- f r a c t i o n l e n g t h}$

In [Slope Bias] scaling the RealWorldValue can be represented by

$\begin{array}{l} r e a l - w o r l d v a l u e = \\ s t o r e d i n t e g e r v a l u e \times (s l o p e a d j u s t m e n t f a c t o r \times 2^{f i x e d e x p o n e n t}) + b i a s \end{array}$

which is equivalent to

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

If any of these properties are updated, the others are modified accordingly.