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The Adaptive Lookup Table (2D Stair-Fit) block creates a two-dimensional
adaptive lookup table by dynamically updating the underlying lookup
table. The block uses the outputs, *y*, of your
system to do the adaptations.

Each indexing parameter *u* may take a value
within a set of adapting data points, which are called *breakpoints. *Two
breakpoints in each dimension define a *cell. *The
set of all breakpoints in one of the dimensions defines a *grid*.
In the two-dimensional case, each cell has four breakpoints and is
a flat surface.

You can use the Adaptive Lookup Table (2D Stair-Fit) block to model time-varying systems with two inputs.

**First input (row) breakpoint set**The vector of values containing possible block input values for the first input variable. The first input vector must be monotonically increasing.

**Second input (column) breakpoint set**The vector of values containing possible block input values for the second input variable. The second input vector must be monotonically increasing.

**Make initial table an input**Selecting this check box forces the Adaptive Lookup Table (2D Stair-Fit) block to ignore the

**Table data (initial)**parameter, and creates a new input port`Tin`. Use this port to input the table data.**Table data (initial)**The initial table output values. This 2-by-2 matrix must be of size (n-1)-by-(m-1), where n is the number of first input breakpoints and m is the number of second input breakpoints.

**Table numbering data**Number values assigned to cells. This matrix must be the same size as the table data matrix, and each value must be unique.

**Adaptation method**Choose

`Sample mean`or`Sample mean with forgetting`. Sample mean averages all the values received within a cell. Sample mean with forgetting gives more weight to the new data. How much weight is determined by the**Adaptation gain**parameter. For more information, see Selecting an Adaptation Method.**Adaptation gain (0 to 1)**A number from 0 to 1 that regulates the weight given to new data during the adaptation. A 0 means short memory (last data becomes the table value), and 1 means long memory (average all data received in a cell).

**Make adapted table an output**Selecting this check box creates an additional output port

`Tout`for the adapted table.**Add adaptation enable/disable/reset port**Selecting this check box creates an additional input port

`Enable`that enables, disables, or resets the adaptive lookup table. A signal value of`0`applied to the port disables the adaptation, and signal value of`1`enables the adaptation. Setting the signal value to`2`resets the table values to the initial table data.**Add cell lock enable/disable port**Selecting this check box creates an additional input port

`Lock`that provides the means for updating only specified cells during a simulation run. A signal value of`0`unlocks the specified cells and signal value of`1`locks the specified cells.**Action for out-of-range input**`Ignore`or`Adapt`by extrapolating beyond the extreme breakpoints.

Adaptive Lookup Table (1D Stair-Fit) | Adaptive Lookup Table (nD Stair-Fit)

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