Approximate one-dimensional function using specified lookup method

Physical Signals/Lookup Tables

The PS Lookup Table (1D) block computes an approximation
to some function `f=f(x)`

given data vectors `x`

and `f`

.
Both the input and the output are physical signals.

The length of the `x`

and `f`

data
vectors provided to this block must match. Also, the `x`

data
vector must be strictly monotonic, either increasing or decreasing.

You define the lookup table by specifying the **Table
grid vector** parameter as a 1-by-`n`

vector
(`x`

data vector) and the **Table values** parameter
as a 1-by-`n`

vector (`f`

data vector).
The block generates output based on the input values using the selected
interpolation and extrapolation methods. You have a choice of two
interpolation methods and two extrapolation methods.

**Table grid vector**Specify the vector of input values as a one-dimensional array. The input values vector must be strictly monotonic, either increasing or decreasing. The values can be nonuniformly spaced. For smooth interpolation, the vector must contain at least three values. For linear interpolation, two values are sufficient.

**Table values**Specify the vector of output values as a one-dimensional array. The output values vector must be of the same size as the input values vector.

**Interpolation method**Select one of the following interpolation methods for approximating the output value when the input value is between two consecutive grid points:

`Linear`

— Uses a linear function. Select this option to get the best performance.`Smooth`

— Uses a modified Akima interpolation algorithm. For details, see

. Select this option to produce a continuous curve with continuous first-order derivatives.`tablelookup`

**Extrapolation method**Select one of the following extrapolation methods for determining the output value when the input value is outside the range specified in the argument list:

`Linear`

— Extends from the edge of the interpolation region linearly. The slope of the linear extrapolation is equal to the slope of the interpolated curve at the edge of the interpolation region.`Nearest`

— Extends from the edge of the interpolation region as a constant. The value of the nearest extrapolation is equal to the value of the interpolated curve at the edge of the interpolation region. Select this option to produce an extrapolation that does not go above the highest point in the data or below the lowest point in the data.

The block has one physical signal input port and one physical signal output port.

Was this topic helpful?