Nonlinearity

Model nonlinearity with lookup tables, approximate mathematical functions by mapping input values to output values

If you are new to modeling nonlinearity, first try using a lookup table block. 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
n-D Lookup TableApproximate n-dimensional function
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

Classes

Simulink.LookupTableStore and share lookup table and breakpoint data, configure the data for ASAP2 and AUTOSAR code generation
Simulink.BreakpointStore and share data for a breakpoint set, configure the data for ASAP2 and AUTOSAR code generation
Simulink.lookuptable.EvenspacingConfigure even spacing set data for lookup table object
Simulink.lookuptable.TableConfigure table data for lookup table object
Simulink.lookuptable.BreakpointConfigure breakpoint set data for lookup table object
Simulink.lookuptable.StructTypeInfoConfigure settings for structure type that lookup table object uses in the generated code

Examples and How To

Enter Breakpoints and Table Data

How to specify breakpoint data sets and table data for lookup table blocks

Edit Lookup Tables

How to 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

This example shows how to use the MATLAB xlsread function in a Simulink model to import data into a lookup table.

Create a Logarithm Lookup Table

Example demonstrating how to work with lookup table blocks

Prelookup and Interpolation Blocks

Provides examples of using Prelookup and Interpolation Using Prelookup blocks together

Update Lookup Table Blocks to New Versions

Process for updating existing models to use current versions of lookup table blocks

Optimize Generated Code for Lookup Table Blocks

Provides tips for optimizing generated code for lookup table blocks

Concepts

About Lookup Table Blocks

Brief overview of lookup table blocks

Anatomy of a Lookup Table

Introduces the components of a lookup table

Lookup Tables Block Library

Describes the various blocks in the Lookup Tables library

Guidelines for Choosing a Lookup Table

How to select the best lookup table for your application

Characteristics of Lookup Table Data

Describes requirements of lookup table data and outlines how to represent discontinuous data

Methods for Approximating Function Values

How to set the method by which lookup table blocks approximate function values

Featured Examples

Interpolation Algorithm Selection and Trajectory Animation

Interpolation Algorithm Selection and Trajectory Animation

Use a dynamic comet plot to visualize the result of changing the interpolation and extrapolation options for a 2-D data set running in an-D Lookup Table block. Algorithm options can be employed in different situations to tradeoff accuracy, smoothness, data size, and performance.

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Using the Prelookup and Interpolation Blocks

Using the Prelookup and Interpolation Blocks

The Prelookup block allows you to minimize the number of index searches performed across a set of look-up tables and also to mix clipping, extrapolation, and index search algorithms within one table calculation.

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Saving Memory in Prelookup and Interpolation Blocks by Using Smaller Data

Saving Memory in Prelookup and Interpolation Blocks by Using Smaller Data

Save memory in Prelookup and Interpolation blocks. The Prelookup and Interpolation Using Prelookup blocks allow the data type storing breakpoints and table data to be set explicitly. Note that the Prelookup block allows the breakpoint data to differ from the input data type, and the Interpolation Using Prelookup block allows the table data to differ from the output data type.

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