Extrema (FPScript)

21.09.2021

Searches for local minima and/or maxima in a data set.

Syntax

Extrema(DataSet, Hysteresis, [ Orientation = EVENT_BOTH ] [ , Operation = EVENT_DEFAULT ])

 

The syntax of the Extrema function consists of the following parts:

Part

Description

DataSet

The data set to be searched.

Permitted data structures are data series, data matrix, signal und signal series. All numeric data types are permitted.

For complex data types the absolute value is formed.

If the argument is a list, then the function is executed for each element of the list and the result is also a list.

Hysteresis

Specifies the minimum amount by which the signal amplitude must rise or fall once a local maximum or minimum has been recognized in order for it to be accepted as a local extreme.

Permitted data structures are scalar value. All numeric data types are permitted. The unit has to be compatible with that of parameter DataSet.

For complex data types the absolute value is formed.

If the argument is a list, then the function is executed for each element of the list and the result is also a list.

Orientation

Specifies whether to search for minima, maxima or both.

The argument Orientation can have the following values:

Constant

Meaning

EVENT_POSITIVE

Search for local maxima only.

EVENT_NEGATIVE

Search for local minima only.

EVENT_BOTH

Search for local minima and maxima.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value EVENT_BOTH.

Operation

Specifies the way the function operates.

The argument Operation can have the following values:

Constant

Meaning

EVENT_INDEX

The indices of the values or points meeting the condition are placed in the result data set.

EVENT_EXTRACT

Only the points or values meeting the condition are transferred into the result data set.

EVENT_SETVOID

The points or values that do not meet the condition are also included in the result data set, but there they are marked as void.

EVENT_DEFAULT

Corresponds to EVENT_SETVOID if a data matrix or signal series is present, and otherwise EVENT_INDEX.

+ EVENT_COMPLEMENT

This constant can be optionally added and then reverses the selected operation. Then, for example, for EVENT_EXTRACT, the points that do not meet the condition are copied.

If the argument is a list, then the first element in the list is taken. If this is also a list, then the process is repeated.

If this argument is omitted, it will be set to the default value EVENT_DEFAULT.

Remarks

The local extrema in the data set are identified using a hysteresis. A value is recognized as a local maximum when the previous values in the data set increase by at least the specified hysteresis amount, and the subsequent values decrease by at least the specified hysteresis amount. A value is recognized as a local minimum when the previous values in the data set decrease by at least the specified hysteresis amount, and the subsequent values increase by at least the specified hysteresis amount.

Available in

FlexPro Basic, Professional, Developer Suite

Examples

Extrema({1, 3, 5, 4, 1}, 1, EVENT_BOTH, EVENT_EXTRACT)

Results in 5.

See Also

NextExtremum Function

Event Isolation Analysis Object

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