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astAxDistance
-
Find the distance between two axis values
- Description:
This function returns a signed value representing the axis increment
from axis value v1 to axis value v2.
For a simple Frame, this is a trivial operation returning the
difference between the two axis values. But for other derived classes
of Frame (such as a SkyFrame) this is not the case.
- Synopsis:
double astAxDistance( AstFrame *this, int axis, double v1, double v2 )
- Parameters:
-
this
-
Pointer to the Frame.
-
v1
-
The first axis value.
-
v2
-
The second axis value.
- Returned Value:
-
astAxDistance
-
The distance between the two axis values.
- Notes:
-
This function will return a "bad" result value (AST__BAD) if
any of the input vaues has this value.
-
A "bad" value will also be returned if this function is
invoked with the AST error status set, or if it should fail for
any reason.
Next: astAxOffset - Add an increment onto a supplied axis value
Up: AST Function Descriptions
Previous: astAxAngle - Returns the angle from an axis, to a line through two points
AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 211
R.F. Warren-Smith & D.S. Berry
30th April 2003
E-mail:ussc@star.rl.ac.uk
Copyright (C) 2003 Central Laboratory of the Research Councils