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hasChangedFrom

Detect change in data from specified value

Description

example

tf = hasChangedFrom(data,value) returns 1 (true) if the value of data is equal to value at the beginning of the previous time step and is a different value at the beginning of the current time step. Otherwise, the operator returns 0 (false). Use this operator in the Requirements Table block.

Examples

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Set the output data a to 1 if the input data M has changed from 1 since the last time step. Otherwise, set a to 0.

Requirements Table block that uses the hasChangedFrom operator to determine the value of output data.

Set the output data a to 1 if the element in row 1 and column 3 of input data M has changed from 1 since the last time step. Otherwise, set a to 0.

Requirements Table block that uses the hasChangedFrom operator to determine the value of output data.

Set the output data a to 1 if one of the fields of the structure struct has changed from the value of structValue since the last time step. Otherwise, set a to 0.

Requirements Table block that uses the hasChangedFrom operator to determine the value of output data.

Set the output data a to 1 if the field struct.field has changed from the value of 1 since the last time step. Otherwise, set a to 0.

Requirements Table block that uses the hasChangedFrom operator to determine the value of output data.

Input Arguments

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Data defined in the Requirements Table block, specified as a:

  • Scalar

  • Matrix or an element of a matrix

  • Structure or a field in a structure

  • Valid combination of structure fields or matrix elements

See Define Data in Requirements Table Blocks.

If data is a matrix, the operator returns true when it detects a change in one of the elements of data. You can also index elements of a matrix by using numbers or expressions that evaluate to a integer.

If data is a structure, the operator returns true when it detects a change in one of the fields of data. You can also index fields in a structure by using dot notation.

The argument data cannot be a nontrivial expression or a custom code variable.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | string | fi | enumerated | bus

Value of the data at previous time step, specified as the same data type of data. value must be an expression that resolves to a value that is comparable with data:

  • If data is a scalar, then value must resolve to a scalar.

  • If data is a matrix, then value must resolve to a matrix with the same dimensions as data.

  • If data is a structure, then value must resolve to a structure whose field specification matches data exactly.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | string | fi | enumerated | bus

Tips

  • If the Requirements Table block writes to the specified data but does not change the value, the hasChangedFrom operator returns false.

Version History

Introduced in R2022a