**Owning Palette:** Lookup Tables Functions

**Requires:** Control Design and Simulation Module

Returns the *y* value, located in a one-dimensional table, that corresponds to an *x* value you specify.

Dialog Box Options |

Block Diagram Inputs |

Block Diagram Outputs |

Parameter | Description |
---|---|

Polymorphic instance | Specifies whether this function is Scalar or Vector. The default value is Scalar. |

Parameters | Lists all the parameters associated with this function. Select a parameter from this list to configure the parameter. When you select a parameter, the parameter and its associated Parameter source control appear in the Parameter Information section of the configuration dialog box. |

Preview | Displays a graphical preview, if available, of the function output or configuration. |

Parameter Information | Contains the parameters you can configure for this function. You must select a parameter from the Parameters list to make that parameter and its associated Parameter source control visible in the Parameter Information section of the configuration dialog box. |

Parameter source | Specifies whether you configure this parameter using the Configuration Dialog Box or a Terminal on the simulation diagram. The default value is Configuration Dialog Box. If you select Terminal, LabVIEW displays an input for that parameter on the simulation diagram, and you can wire values to that input to configure this function programmatically. If you select Configuration Dialog Box, LabVIEW removes that input from the simulation diagram. You then must set the value for this parameter inside the configuration dialog box. |

Method | Specifies the interpolation method the lookup table uses. You can choose from the following options:**Interpolate/Extrapolate**—(Default) If the given**X Val**lies between two points in the**LUT X**set, the result is a linear interpolation of the**LUT Data**values that correspond to the two**LUT X**points. If the given**X Val**lies outside the range of the**LUT X**set, the result is a linear extrapolation of the**LUT Data**values that correspond to the nearest two**LUT X**points. For an interpolation example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the two**LUT X**values that are nearest to the given**X Val**are 1 and 5. These points represent the*x*coordinates of a set of points on a line. The**LUT Data**values that correspond to those**LUT X**values are 2 and 8, which represent the corresponding*y*coordinates of the points on the line. This function calculates the slope of the line as (8 – 2) / (5 – 1) = 1.5. This function then uses the slope to interpolate linearly the*y*value when*x*is 4. Therefore, the**Result**is 6.5. For an extrapolation example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 6, the two**LUT X**values that are nearest to the given**X Val**are 1 and 5. These points represent the*x*coordinates of a set of points on a line. The**LUT Data**values that correspond to those**LUT X**values are 2 and 8, which represent the corresponding*y*coordinates of the points on the line. This function calculates the slope of the line as (8 – 2) / (5 – 1) = 1.5. This function then uses the slope to extrapolate linearly the*y*value when*x*is 6. Therefore, the**Result**is 9.5.**Interpolate**—If the given**X Val**lies between two points in the**LUT X**set, the result is a linear interpolation of the**LUT Data**values that correspond to the two**LUT X**points. If the given**X Val**is out of range, the result is the**LUT Data**value that corresponds to the value of**LUT X**closest to**X Val**.**Nearest**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is nearest to the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that is nearest to the given**X Val**is 5. The**LUT Data**value that corresponds to an**LUT X**value of 5 is 8. Therefore, the**Result**is 8.**Below**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is less than the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that lies directly below the given**X Val**is 1. The**LUT Data**value that corresponds to an**LUT X**value of 1 is 2. Therefore, the**Result**is 2.**Above**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is greater than the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that lies directly above the given**X Val**is 5. The**LUT Data**value that corresponds to an**LUT X**value of 5 is 8. Therefore, the**Result**is 8.
Interpolate/Extrapolate for Method and the given value is out of range, this function returns the value of the end point that is closest to the given value. |

LUT X | Specifies the set of x values that correspond to the y data points in LUT Data. The elements of LUT X must be monotonically increasing or equal such that LUT X[i] ≥ LUT X[j] if i > j. |

LUT Data | Specifies a one-dimensional table of y data points that correspond to the values you specify for the LUT X parameter. |

Parameter | Description |
---|---|

Method | Specifies the interpolation method the lookup table uses. You can choose from the following options:**Interpolate/Extrapolate**—(Default) If the given**X Val**lies between two points in the**LUT X**set, the result is a linear interpolation of the**LUT Data**values that correspond to the two**LUT X**points. If the given**X Val**lies outside the range of the**LUT X**set, the result is a linear extrapolation of the**LUT Data**values that correspond to the nearest two**LUT X**points. For an interpolation example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the two**LUT X**values that are nearest to the given**X Val**are 1 and 5. These points represent the*x*coordinates of a set of points on a line. The**LUT Data**values that correspond to those**LUT X**values are 2 and 8, which represent the corresponding*y*coordinates of the points on the line. This function calculates the slope of the line as (8 – 2) / (5 – 1) = 1.5. This function then uses the slope to interpolate linearly the*y*value when*x*is 4. Therefore, the**Result**is 6.5. For an extrapolation example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 6, the two**LUT X**values that are nearest to the given**X Val**are 1 and 5. These points represent the*x*coordinates of a set of points on a line. The**LUT Data**values that correspond to those**LUT X**values are 2 and 8, which represent the corresponding*y*coordinates of the points on the line. This function calculates the slope of the line as (8 – 2) / (5 – 1) = 1.5. This function then uses the slope to extrapolate linearly the*y*value when*x*is 6. Therefore, the**Result**is 9.5.**Interpolate**—If the given**X Val**lies between two points in the**LUT X**set, the result is a linear interpolation of the**LUT Data**values that correspond to the two**LUT X**points. If the given**X Val**is out of range, the result is the**LUT Data**value that corresponds to the value of**LUT X**closest to**X Val**.**Nearest**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is nearest to the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that is nearest to the given**X Val**is 5. The**LUT Data**value that corresponds to an**LUT X**value of 5 is 8. Therefore, the**Result**is 8.**Below**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is less than the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that lies directly below the given**X Val**is 1. The**LUT Data**value that corresponds to an**LUT X**value of 1 is 2. Therefore, the**Result**is 2.**Above**—If the given**X Val**lies between two points in the**LUT X**set, the result is the**LUT Data**value that corresponds to the**LUT X**point whose value is greater than the given**X Val**. For example, given**LUT X**is [0 1 5],**LUT Data**is [4 2 8], and**X Val**is 4, the**LUT X**value that lies directly above the given**X Val**is 5. The**LUT Data**value that corresponds to an**LUT X**value of 5 is 8. Therefore, the**Result**is 8.
Interpolate/Extrapolate for Method and the given value is out of range, this function returns the value of the end point that is closest to the given value. |

LUT X | Specifies the set of x values that correspond to the y data points in LUT Data. The elements of LUT X must be monotonically increasing or equal such that LUT X[i] ≥ LUT X[j] if i > j. |

LUT Data | Specifies a one-dimensional table of y data points that correspond to the values you specify for the LUT X parameter. |

X Val | Specifies the x value to locate in the LUT Data table. |

Parameter | Description |
---|---|

Result | Returns the y value in the LUT Data table that corresponds to the value you specify for the X Val parameter. If a direct match does not exist, this function operates according to the value you specify for the Method parameter. |

All input/output pairs of this function have direct feedthrough behavior.

Refer to the SimEx LUT 1D VI in the labview\examples\Control and Simulation\Simulation\LUT directory for an example of using the Lookup Table 1D VI.