### Series Functions

A series function defines a mathematical relation that associates one destination series with one or multiple source series. A series function always involves two types of series components: the position component and the value component. The series function associates the value component of the destination series with the value component(s) of the source series via a mathematical function (e.g. add, subtract, integrate, differentiate, Fourier transform, etc). The data in the value component of the destination series of the series function are the values of this mathematical function of the data in the value component(s) of the source series of the series function. The data in the position component(s) of the source series of the series function are usually copied directly to the position component of the destination source of the series function except for the case of the FFT series function where the data in the position component are also subject to the so-called time to frequency transform. Sometimes, not all data in the source series are used in the series function. In such cases, the user selects a part of the data in the source series by specifying a range for the data in the position component(s) of  the source series - only data in the position component(s) of the source series that are in this specific range will be used in the series function. This range of values is called the domain of the series function.

It is important not to confuse the position/value components of the source and destination series of a series function with the Position/Value series components - the former are used in the series function context to refer to the roles of the components in the series function while the latter are used in the series context to refer to the roles of the components in the specific series. If a series function involves only series with two mandatory Position and Value series components, the Position series component of the source and the destination series will be used as the position component of the series function and the Value series component of the source and the destination series as the value component of the series function. If there are more than two mandatory series components in the source series, the user may specify one as the value component of the source series of the series function with the Value combo-box of the Series Function dialog box

In a series function,  the source series serve as the data source for the destination series. To apply a series function to the active series, select the series function type on the Series Function sub menu of the Graph menu (which is also the context menu of the graph document) to open the Series Function dialog box with which a new series function can be created and applied to the active series. If the active series happens to be the destination series of a series function, an Edit Function menu command will appear on the Series Function sub menu of the Graph menu - selecting it opens the Series Function dialog box with which the user can edit the series function that produces the active series.

The current version of DataScene supports the following 20 series functions: