Curve Using Prelookup

R2026b

Use previously calculated index and fraction values to accelerate approximation of one-dimensional function

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  • Curve Using Prelookup block

Libraries:
AUTOSAR Blockset / Classic Platform / Library Routines / Interpolation

Description

The Curve Using Prelookup block uses the calculated index and fraction values from a Prelookup block to interpolate a one-dimensional (1-D) lookup table, which represents sampled values of an approximated function. The output of this block is the result of the approximated function using the current inputs.

The Prelookup and Curve Using Prelookup blocks have distributed algorithms that, when used together, perform the same algorithm operation as the Curve block. By using the Prelookup and Curve Using Prelookup blocks together you have greater flexibility and more efficient simulation and code generation than when just using the Curve block.

If you select the AUTOSAR 4.x code replacement library (CRL) for your AUTOSAR model, code generated from this block is replaced with the AUTOSAR library routine that you configure in the block parameters dialog box.

Examples

AUTOSAR Code Replacement Library Example for IFX and IFL Function Replacement

AUTOSAR Code Replacement Library Example for IFX and IFL Function Replacement

The Code Replacement Viewer lists AUTOSAR floating-point interpolation (IFL) and fixed-point interpolation (IFX) library routines that you can generate in lookup table C code. For replacing lookup table C code with IFL or IFX library routines, AUTOSAR Blockset provides lookup table blocks that are pre-configured for AUTOSAR code generation. You insert a block such as Curve, or Map in your model, then open the block dialog box and configure the block to generate a specific interpolation routine required by your design. For more information, see Configure Lookup Tables for AUTOSAR Calibration and Measurement.

Ports

Input

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Inputs to the kf1 port contain index k and fraction f, specified as either Ifx_DPResultU16_Type or Ifl_DPResultF32_Type.

When Targeted Routine Library is set to IFX (fixed-point) then the port is set to data type Ifx_DPResultU16_Type.

When Targeted Routine Library is set to IFL (floating-point) then the port is set to data type Ifl_DPResultF32_Type.

Output

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Approximation of the one-dimensional function computed by interpolating table data that uses values from the input index, k, and the fraction, f.

When Targeted Routine Library is set to IFL (floating-point) then the only valid data type is single.

When Targeted Routine Library is set to IFX (fixed-point)then you can the values of the Port 1 can be one of these data types: int8, uint8, int16, uint16, int32, uint32, and fixed-point data types.

Data Types: single | int8 | uint8 | int16 | uint16 | int32 | uint32 | fixed point

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

If you select the AUTOSAR 4.x code replacement library (CRL) for your model, code generated from this block is replaced from the selected AUTOSAR routine library. This parameter enables you to choose either fixed-point (IFX) or floating-point (IFL) code replacement and validation checks.

Programmatic Use

Block Parameter: TargetRoutineLibrary
Type: character vector | string
Values:'IFL (floating-point)' | 'IFX (fixed-point)'

This parameter is read-only.

This parameter reflects the name of the AUTOSAR code replacement library (CRL) routine used to replace the code generated by this block. The naming convention includes the targeted routine library, interpolation method, and block type. This parameter is reference-only and must not be edited.

Dependencies

  • When the Targeted Routine Library is set to IFX (fixed-point) the value defaults to Ifx_IpoCur.

  • When the Targeted Routine Library is set to IFL (floating-point) the value defaults to Ifl_IpoCur.

Programmatic Use

Block Parameter: TargetedRoutine
Type: character vector
Values:'Ifl_IpoCur' | 'Ifx_IpoCur'

Table Specification

Specify whether to enter table data directly or use a Simulink.LookupTable object. If you set this parameter to:

  • Explicit values, the Table Data parameter and Data Types tab are visible in the dialog box.

  • Lookup table object, the Name parameter is visible in the dialog box.

Programmatic Use

Block Parameter: TableSpecification
Type: character vector | string
Values: "Explicit values" | "Lookup table object"
Default: "Explicit values"

Specify the name of a Simulink.LookupTable object. The Simulink.LookupTable object references the Simulink.Breakpoint objects specified in the Prelookup blocks. If a Simulink.LookupTable object does not exist, click the action button and select Create. The corresponding parameters of the new Simulink.LookupTable object are populated with the block information.

Dependencies

To enable this parameter, set Data Specification to Lookup table object.

Programmatic Use

Block Parameter: LookupTableObject
Type: character vector
Value: Simulink.LookupTable object
Default: '[]'

Enter the table of output values.

During simulation, the matrix size must be one-dimensional. However, during block diagram editing, you can enter an empty matrix (specified as []) or an undefined workspace variable. This technique lets you postpone specifying a correctly dimensioned matrix for the table data and continue editing the block diagram.

Dependencies

To enable this parameter, set Data specification to Explicit values.

Programmatic Use

Block Parameter: Table
Type: character vector
Values: matrix of table values
Default: '[1 2 4]'

Click this button to open the Lookup Table Editor.

Algorithm

Specify the method that the block uses to interpolate table data. You can select Linear point-slope or Flat. For more information, see Interpolation Methods.

Programmatic Use

Block Parameter: InterpMode
Type: character vector | string
Values: "Flat" | "Linear point-slope"
Default: "Linear point-slope"

Data Types

To enable this tab, on the Table Specification tab, set Data Specification to Explicit values.

Specify the table data type. The block validates that the selected types are compatible with the specification of the targeted routine.

When Targeted Routine Library is set to IFL (floating-point) then the only valid data type is single.

When Targeted Routine Library is set to IFX (fixed-point)then you can set the data type to:

  • Rules that inherit a data type: Inherit: Same as output, Inherit: Inherit from 'Table data'.

  • One of these built-in data types: int8, uint8, int16, uint16, int32, and uint32.

  • The name of a data type object, for example, a Simulink.NumericType object.

  • An expression that evaluates to a data type. For example, the software provides these common fixed-point data type expressions: fixdt(1,16), fixdt(1,16,0), or fixdt(1,16,2^0,0).

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant.

Programmatic Use

Block Parameter: TableDataTypeStr
Type: character vector | string
Values: "Inherit: Inherit from 'Table data'" | "Inherit: Same as output" | "single" | "int8" | "uint8" | "int16" | "uint16" | "int32" | "uint32" | "fixdt(1,16)" | "fixdt(1,16,0)" | "fixdt(1,16,2^0,0)" | "<data type expression>"
Default: "Inherit: Same as output"

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019a

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See Also

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