This attribute controls the appearance of an annotated coordinate grid (drawn with the AST_GRID routine) by determining the logarithmic interval between the " major" axis values of a Plot, at which (for example) major tick marks are drawn. It takes a separate value for each physical axis of the Plot so that, for instance, the setting " LogGap(2)=100.0" specifies the ratio between adjacent major values along the second axis. The LogGap attribute is only used when the LogTicks attribute indicates that the spacing between major axis values is to be logarithmic. If major axis values are linearly spaced then the gap is specified using attribute Gap.

The LogGap value supplied will be rounded to the nearest power of 10. The reciprocal of the supplied value may be used if this is necessary to produce usable major axis values. If a zero or negative value is supplied, an error will be reported when the grid is drawn. The default behaviour is for the Plot to generate its own LogGap value when required, based on the range of axis values to be represented.

Plot

• The LogGap value is a ratio between axis values and is therefore dimensionless.

• If no axis is specified, (e.g. " LogGap" instead of " LogGap(2)" ), then a " set" or " clear" operation will affect the attribute value of all the Plot axes, while a " get" or " test" operation will use just the LogGap(1) value.