Main Content

Lookup Tables

Lookup table blocks such as Cosine and Sine

Use blocks from the Lookup Tables library to model nonlinearity. Lookup table blocks use arrays of data to map input values to output values, approximating mathematical functions. To approximate a function in N variables, use the n-D Lookup Table block:

Blocks

1-D Lookup TableApproximate one-dimensional function
2-D Lookup TableApproximate two-dimensional function
Direct Lookup Table (n-D)Index into n-dimensional table to retrieve element, vector, or 2-D matrix
Interpolation Using PrelookupUse precalculated index and fraction values to accelerate approximation of N-dimensional function
Lookup Table DynamicApproximate a one-dimensional function using dynamic table
PrelookupCompute index and fraction for Interpolation Using Prelookup block
Sine, CosineImplement fixed-point sine or cosine wave using lookup table approach that exploits quarter wave symmetry
n-D Lookup TableApproximate n-dimensional function

Examples and How To

Enter Breakpoints and Table Data

Specify breakpoint data sets and table data for lookup table blocks.

Edit Lookup Tables

Change the elements of lookup tables.

Import Lookup Table Data from MATLAB

You can import table and breakpoint data from variables in the MATLAB workspace by referencing them in the Table and Breakpoints tab of the dialog box.

Import Lookup Table Data from Excel

Import data into a lookup table with the xlsread function.

Create a Logarithm Lookup Table

Work with lookup table blocks.

Prelookup and Interpolation Blocks

Use Prelookup and Interpolation Using Prelookup blocks together.

Row-Major Algorithm in Existing Models Containing Lookup Table Blocks

Update existing models to use row-major layout.

Update Lookup Table Blocks to New Versions

Update existing models to use current versions of lookup table blocks.

Concepts

About Lookup Table Blocks

A lookup table block uses an array of data to map input values to output values, approximating a mathematical function.

Anatomy of a Lookup Table

Breakpoint data sets and table data are components of a lookup table.

Lookup Tables Block Library

Choose among the various blocks in the Lookup Tables library.

Guidelines for Choosing a Lookup Table

Select the best lookup table for your application.

Characteristics of Lookup Table Data

Comply with lookup table data requirements and represent discontinuous data.

Methods for Approximating Function Values

Set the method by which lookup table blocks approximate function values.

Optimize Generated Code for Lookup Table Blocks

Optimize generated code for lookup table blocks.