Lookup Tables
R2026bUse blocks from the Lookup Tables library to model nonlinear behavior. 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.
To add blocks from this library to your model, see Add Blocks to Models.
To manage the lookup tables in your environment, consider using the Lookup Table Editor. Watch How to Use the Lookup Table Editor (5min 9sec).
Blocks
 | 1-D Lookup Table | Approximate one-dimensional function |
 | 2-D Lookup Table | Approximate two-dimensional function |
 | Direct Lookup Table (n-D) | Index into n-dimensional table to retrieve element, vector, or 2-D matrix |
 | Interpolation Using Prelookup | Use precalculated index and fraction values to accelerate approximation of N-dimensional function |
 | Lookup Table Dynamic | (Not recommended) Approximate a one-dimensional function using dynamic table |
 | Prelookup | Compute index and fraction for Interpolation Using Prelookup block |
 | Sine | Implement fixed-point sine or cosine wave using lookup table approach that exploits quarter wave symmetry |
 | n-D Lookup Table | Approximate n-dimensional function |
Tools
| Lookup Table Editor | Create, edit, and manage lookup tables in models (Since R2022a) |
| Library Browser | Find and add blocks to model |
Topics
Understand Lookup Tables
- Lookup Table Overview
Learn about the anatomy and characteristics of Lookup Table blocks, objects, and tools. - Configure Lookup Table Block for Logarithmic Operation
Configure an n-D Lookup Table block for logarithmic operation with the common logarithmic base (base 10). - Add Blocks to Models
Use the Library Browser and quick insert menu to insert blocks.
Implement Lookup Tables to Approximate Nonlinear Systems
- Choose Lookup Table Blocks Based on Input, Breakpoint and Output Data
Select the Lookup Table block best suited for your application. - Enter Breakpoints and Table Data
Specify breakpoint vectors and table data for a lookup table. - Specify Breakpoint and Table Data with Variable Size and Symbolic Dimensions
Specify breakpoint and table data that changes size during model simulation or represented by symbolic dimensions. - Import Data to Lookup Table
Import table and breakpoint data from MATLAB® workspace and Excel® spreadsheets. - Choose Numerical Methods to Approximate Function Values
Set the method by which Lookup Table blocks approximate function values. - Optimize Lookup Tables for Memory-Efficiency (Fixed-Point Designer)
Optimize Lookup Tables using the Lookup Table Optimizer. - Use Row-Major Algorithms for Lookup Table Blocks
Use row-major algorithms for C/C++ code generation from models containing Lookup Table blocks. - Optimize Generated Code for Lookup Table Blocks
Optimize code for Lookup Table blocks.
Edit and Visualize Lookup Tables
- Edit and Visualize Lookup Table Data
View, add, delete, or update lookup table data.
Update Lookup Tables from Previous Releases
- Update Lookup Table Blocks to New Versions
Update existing models to use current versions of lookup table blocks.
Related Information
Featured Examples
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Using the Prelookup and Interpolation Using Prelookup Blocks
Use the Prelookup and Interpolation Using Prelookup blocks.
Saving Memory in Prelookup and Interpolation Using Prelookup Blocks by Using Smaller Data
Save memory in Prelookup and Interpolation Using Prelookup blocks. The Prelookup and Interpolation Using Prelookup blocks allow you to explicitly set data type for storing breakpoints and table data, respectively. 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.
Sharing Parameters in Prelookup and Interpolation Blocks
How Prelookup and Interpolation blocks share their parameter data in generated code.
Shared Utility Functions for Prelookup Blocks
How Prelookup blocks share utility functions. The utility functions generated by the Prelookup block are determined by the target data type of the block's inputs, outputs, and breakpoint parameter, as well as the Index search method and Integer rounding mode. Even if the two Prelookup blocks have different input data type, output data type, and breakpoint data type, they use shared utility functions.
High Precision Calculations in Interpolation Block
Perform high precision calculations in the Interpolation Using Prelookup block using internal rules. The Interpolation block allows the data type for intermediate results to be set.
