Support calculations involving sample time
Math Operations
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. If the input signal
is constant, Simulink assigns a finite sample time to the block
based on its connectivity and context.
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
, that
value does not appear 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
The Weighted Sample Time Math block accepts signals of the following data types:
Floating point
Builtin integer
Fixed point
Boolean
For more information, see Data Types Supported by Simulink in the Simulink documentation.
The Main pane of the Weighted Sample Time Math block dialog box appears as follows:
Specify operation to use: +
, 
, *
, /
, Ts
Only
, or 1/Ts Only
.
Enter the weight of sample time.
Select one of two modes: online calculations or offline scaling
adjustment. This parameter is visible only when you set Operation to *
or /
.
Result of (Ts * w)  Output Data Type of Two Modes  Block Execution 

A power of 2, or an integer value  The same, when Output data type is Inherit:
Inherit via internal rule  Equally efficient in both modes 
Not power of 2 and not an integer value  Different  More efficient for the offline scaling mode 
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:
Tip The Saturate on integer overflow parameter is visible only if:

Specify whether the block inherits the output data type by an internal rule or back propagation.
Tip If you enter an expression in the edit field, the expression must evaluate to one of the two inherit rules. 
Specify the rounding mode for fixedpoint operations. For more information, see Rounding. in the FixedPoint Designer™ documentation.
Action  Reasons for Taking This Action  What Happens for Overflows  Example 

Select this check box.  Your model has possible overflow, and you want explicit saturation protection in the generated code.  Overflows saturate to either the minimum or maximum value that the data type can represent.  The maximum value that the 
Do not select this check box.  You want to optimize efficiency of your generated code. You want to avoid overspecifying how a block handles outofrange signals. For more information, see Checking for Signal Range Errors.  Overflows wrap to the appropriate value that is representable by the data type.  The maximum value that the 
When you select this check box, saturation applies to every internal operation on the block, not just the output or result. Usually, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.
Data Types  Double  Single  Boolean  Base Integer  FixedPoint 
Direct Feedthrough  For all math operations except 
Multidimensional Signals  No 
VariableSize Signals  No 
ZeroCrossing Detection  No 
Code Generation  Yes 