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FixPt Matrix Gain

Multiply the input by a constant matrix.

Description

The FixPt Matrix Gain block is a masked S-function that multiplies the input by a constant matrix (referred to as the matrix gain). The block generates its output by multiplying the input by a specified matrix

\(y=Ku\)

where \(K\) is the matrix gain and \(u\) is the input. If the matrix has m rows and n columns, then the input to this block should be a vector of length n. The output is a vector of length m.

Dialog Box Parameters

  • Gain matrix value - Specify as a scalar or vector. The parameter is converted from doubles to the specified data type offline using round-to-nearest and saturation.
  • Parameter data type - Any data type supported by the Fixed-Point Blockset.
  • Parameter scaling - Radix point-only or slope/bias scaling. The gain can be scaled using the constant matrix scaling modes for maximizing precision. These scaling modes are available only for generalized fixed-point data types. Refer to the section below for details.
  • Output data type and scaling - Specify the output data type and scaling via the dialog box, or inherit the data type and scaling from the driving block or by back propagation.
  • Output data type - Any data type supported by the Fixed-Point Blockset.
  • Output scaling - Radix point-only or slope/bias scaling. These scaling modes are available only for generalized fixed-point data types.
  • Lock output scaling so autoscaling tool can't change it - If checked, the output scaling is locked. This feature is available only for generalized fixed-point output.
  • Round toward - Rounding mode for the fixed-point output.
  • Saturate to max or min when overflows occur - If checked, fixed-point overflows saturate. Otherwise, they wrap.
  • Override data types(s) with doubles - If checked, the parameter output data type values are overridden with doubles.
  • Log minimums and maximums - If checked, minimum and maximum simulation values are logged to the workspace.

Parameter Scaling

If Parameter data type is a generalized fixed-point number such as sfix(16), the Parameter scaling list provides these scaling modes:

  • Use Specified Scaling - Uses the slope/bias or radix point-only scaling specified for the editable Parameter scaling parameter (for example, \(2^{-10}\)).
  • Use Best Precision: Element-wise - Produces radix points such that the precision is maximized for each element of the Gain matrix value matrix.
  • Use Best Precision: Row-wise - Produces a common radix point for each element of a Gain matrix value row based on the best precision for the largest value of that row.
  • Use Best Precision: Column-wise - Produces a common radix point for each element of a Gain matrix value column based on the best precision for the largest value of that column.
  • Use Best Precision: Matrix-wise - Produces a common radix point for each element of the Gain matrix value matrix based on the best precision for the largest value of the matrix.

Characteristics

Characteristic Description
Input Port Any data type supported by the blockset
Output Port Any data type supported by the blockset
Direct Feedthrough Yes
Sample Time Inherited
Scalar Expansion Of one input if the other is a vector
States 0
Vectorized Yes