Check Discrete Gradient

Check that absolute value of difference between successive samples of discrete signal is less than upper bound

  • Library:
  • Simulink / Model Verification

    HDL Coder / Model Verification

Description

The Check Discrete Gradient block checks each signal element at its input to determine whether the absolute value of the difference between successive samples of the element is less than an upper bound. Specify the value of the upper bound (1 by default) by setting the Maximum gradient parameter. If the verification condition is true, the block does nothing. Otherwise, the block halts the simulation, by default, and displays an error in the Diagnostic Viewer.

Enable or disable all model verification blocks by changing the Model Verification block enabling setting in the Configuration Parameters.

Use the blocks in the Model Verification library to facilitate creation of self-validating models. For example, you can use model verification blocks to test that signals do not exceed specified limits during simulation. When you are satisfied that a model is correct, you can turn error checking off by disabling the verification blocks. You do not have to remove them from the model. If you need to modify a model, you can temporarily turn the verification blocks back on to ensure that your changes do not break the model.

Ports

Input

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Input signal the block checks to determine if the difference of each element between sucessive samples is less than the upper bound. Specify the upper bound by setting the Maximum gradient parameter.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | fixed point

Output

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Output signal at each time step that is true (1) if the assertion succeeds, and false (0) if the assertion fails. If, in the Configuration Parameters, you select Implement logic signals as Boolean data, then the output data type is a Boolean. Otherwise the data type of the signal is a double.

Dependencies

To enable this output port, select the Output assertion signal parameter check box.

Data Types: double | Boolean

Parameters

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Specify the upper bound on the allowed gradient of the input signal.

Command-Line Information

Parameter: gradient
Type: character vector
Values: real scalar
Default: '1'

Clearing this check box disables the block and causes the model to behave as if the block does not exist. You can set the Model Verification block enabling setting in the Configuration Parameters to enable or disable all model verification blocks in a model regardless of the setting of this option.

Command-Line Information

Parameter: enabled
Type: character vector
Values: 'on' | 'off'
Default: 'on'

Specify a MATLAB® expression to evaluate when the assertion fails. Because the expression is evaluated in the MATLAB workspace, define all variables used in the expression in that workspace.

Command-Line Information

Parameter: callback
Type: character vector
Values: MATLAB expression
Default: ' '

Select this check box to indicate that the block halts simulation when the check fails. Clear to indicate that the software displays a warning and continues the simulation.

Command-Line Information

Parameter: stopWhenAssertionFail
Type: character vector
Values: 'on' | 'off'
Default: 'on'

Selecting this check box causes the block to output a Boolean signal that is true (1) at each time step if the assertion succeeds and false (0) if the assertion fails. The data type of the output signal is Boolean if you have selected the Implement logic signals as Boolean data check box on the Configuration Parameters dialog box. Otherwise the data type of the output signal is double.

Command-Line Information

Parameter: export
Type: character vector
Values: 'on' | 'off'
Default: 'off'

Specify the type of icon used to display this block in a block diagram. The graphic option displays a graphical representation of the assertion condition on the icon. The text option displays a mathematical expression that represents the assertion condition. If the icon is too small to display the expression, the text icon displays an exclamation point. To see the expression, enlarge the block.

Command-Line Information

Parameter: icon
Type: character vector
Values: 'graphic' | 'text'
Default: 'graphic'

Block Characteristics

Data Types

double | fixed point | integer | single

Direct Feedthrough

no

Multidimensional Signals

yes

Variable-Size Signals

no

Zero-Crossing Detection

no

Extended Capabilities

PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.

Fixed-Point Conversion
Convert floating-point algorithms to fixed point using Fixed-Point Designer™.

Introduced before R2006a