DADiSP Worksheet Functions > Function Categories > Query Functions > XOFFSET

 

XOFFSET

Purpose:

Returns the x offset of a series or table.

Syntax:

XOFFSET(series)

series

-

Optional. A series or table. Defaults to the current Window.

Returns:

A real.

Example:

xoffset(gsin(20,.05))

 

returns 0.0, the offset of the series.

Example:

W1: gsin(20, .05)

W2: extract(w1, -10, -1)

xoffset(w2)

 

returns –0.55, the offset produced by extracting the data prior to the first sample.

Remarks:

When referencing a table, XOFFSET returns the x offset of the first column in the table.

 

Many series have X values that are monotonically rising by a constant X increment such that:

 

image\xy01.gif

 

A series with X values of this form is referred to as an interval series. Because any X value from an interval series can be computed with:

 

image\XY02.gif

 

an interval series requires only the DELTAX and XOFFSET values to determine the X values. Thus, for an interval series, explicit X values are not necessary, decreasing the data storage requirements by a factor of 2. Also, because the X values for an interval series are regularly monotonic, speed optimizations for plotting and computations are available.

 

See XY to create a series with irregularly spaced X values.

See Also:

DELTAX

DELTAY

RATE

SETDELTAX

SETDELTAY

SETXOFFSET

SETYOFFSET

XY

YOFFSET