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Weighted Sample Time Math - Support calculations involving sample time

Library

Math Operations

Description

The Weighted Sample Time Math block adds, subtracts, multiplies, or divides its input signal, u, by a weighted sample time Ts. If the input signal is continuous, Ts is the sample time of the Simulink model. Otherwise, Ts is the sample time of the discrete input signal.

You specify the math operation with the Operation parameter. Additionally, you can specify to use only the weight with either the sample time or its inverse.

Enter the weighting factor in the Weight value parameter. If the weight, w, is 1, Simulink software refrains from displaying it in the equation on the block icon.

The block computes its output using the precedence rules for MATLAB operators (see Operator Precedence). For example, if the Operation parameter specifies +, the block calculates output using this equation:

u + (Ts * w)

However, if the Operation parameter specifies /, the block calculates output using this equation:

(u / Ts) / w

Data Type Support

The Weighted Sample Time Math block accepts signals of any numeric data type supported by Simulink software, including fixed-point data types.

Parameters and Dialog Box

The Main pane of the Weighted Sample Time Math block dialog box appears as follows:

Operation

Specify operation to use: +, -, *, /, Ts Only, or 1/Ts Only.

Weight value

Enter weight of sample time.

Implement using

Specify online calculations or offline scaling adjustment. This parameter is visible only if you specify * or / as the Operation parameter.

Note   When the Implement using parameter is not visible, operations default to online calculations.

The Signal Attributes pane of the Weighted Sample Time Math block dialog box appears as follows:

Output data type

Specify whether the block inherits the output data type by an internal rule or back propagation.

Integer rounding mode

Select the rounding mode for fixed-point operations. For more information, see Rounding in the Simulink Fixed Point User's Guide.

Saturate on integer overflow

Select to have fixed-point overflows saturate. Otherwise, they wrap.

When you select this check box, saturation applies to every internal operation on the block, not just the output or result. In general, the code generation process can detect when overflow is not possible, in which case, no saturation code is necessary.

This parameter is visible only if:

• The Operation parameter specifies + or -.

• The Operation parameter specifies * or / and the Implement using parameter specifies Online Calculations.

Characteristics

Direct Feedthrough	For all math operations options except Ts and 1/Ts
Scalar Expansion	No, the weight is always a scalar

Weighted Sample Time

While Iterator

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