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MaxAxes - Maximum number of Frame axes to match

Description:
This attribute controls how a Frame behaves when it is used (by AST_FINDFRAME) as a template to match another (target) Frame. It specifies the maximum number of axes that the target Frame may have in order to match the template.

Normally, this value will equal the number of Frame axes, so that a template Frame will only match another Frame with the same number of axes as itself. By setting a different value, however, the matching process may be used to identify Frames with specified numbers of axes.

Type:
Integer.
Class Applicability:
Frame
The default MaxAxes value for a Frame is equal to the number of Frame axes (Naxes attribute).
CmpFrame
The MaxAxes attribute of a CmpFrame defaults to a large number (1000000) which is much larger than any likely number of axes in a Frame. Combined with the MinAxes default of zero (for a CmpFrame), this means that the default behaviour for a CmpFrame is to match any target Frame that consists of a subset of the axes in the template CmpFrame. To change this so that a CmpFrame will only match Frames that have the same number of axes, you should set the CmpFrame MaxAxes and MinAxes attributes to the number of axes in the CmpFrame.
FrameSet
The MaxAxes attribute of a FrameSet is the same as that of its current Frame (as specified by the Current attribute).
Notes:
  • When setting a MaxAxes value, the value of the MinAxes attribute may also be silently changed so that it remains consistent with (i.e. does not exceed) the new value. The default MaxAxes value may also be reduced to remain consistent with the MinAxes value.

  • If a template Frame is used to match a target with a different number of axes, the MatchEnd attribute of the template is used to determine how the individual axes of each Frame should match.


next up previous 264
Next: MeshSize - Number of points used to represent the boundary of a Region
Up: AST Attribute Descriptions
Previous: MatchEnd - Match trailing axes?

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council