# SETDELTAX

## Purpose:

Modifies the spacing between points on
the horizontal axis.

## Syntax:

SETDELTAX(series,
dx)

series |
- |
Optional. A series or table, defaults to the
current Window. |

dx |
- |
A real, the new delta X value. |

## Example:

setdeltax(0.2)

sets the current DELTAX
to 0.2, i.e. 2 seconds per sample or a sample rate of 5 samples per second
if the horizontal units are seconds.

## Example:

a = 1..100;

setdeltax(a, 3);

sets the DELTAX
of variable **a** to 3, i.e. 3 seconds
per sample or a sample rate of 1/3 samples per second if the horizontal
units are seconds.

## Remarks:

When referencing a table, SETDELTAX changes
the deltax of each column of data to the new deltax. For example,

ravel({1,
3, 5}, grandom(3, 0.1)); setdeltax(0.5)

sets the current deltax of the generated
series in column 1 as well as the generated random series in column 2
to 0.5.

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

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:

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

SETDELTAY

SETHUNITS

SETXOFFSET

SETYOFFSET

XOFFSET

XY

YOFFSET