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coordsys.convert - Function

	Package	general
	Module	images
	Tool	coordsys

Convert a numeric mixed coordinate

Synopsis
convert(coordin, absin, dopplerin, unitsin, absout, dopplerout, unitsout, shape)

Arguments

coordin	in	Input coordinate
		Allowed:	Numeric vector
absin	in	Are input coordinate elements absolute ?
		Allowed:	Boolean vector
		Default:	All T
dopplerin	in	Input doppler type for velocities
		Allowed:	String
		Default:	'radio'
unitsin	in	Input units
		Allowed:	String vector
		Default:	Native
absout	in	Are output coordinate elements absolute ?
		Allowed:	Boolean vector
		Default:	All T
dopplerout	in	Output doppler type for velocities
		Allowed:	String
		Default:	'radio'
unitsout	in	Output units
		Allowed:	String vector
		Default:	Native
shape	in	Image shape
		Allowed:	Integer vector
		Default:	Unused

Returns
Numeric vector or fail

Description

This function converts between mixed pixel/world/abs/rel numeric coordinates. The input and output coordinates are specified via a numeric vector giving coordinate values, a string vector giving units, a boolean vector specifying whether the coordinate is absolute or relative (to the reference pixel) and doppler strings specifying the doppler convention for velocities.

The units string may include pix for pixel coordinates and velocity units (i.e. any unit consistent with m/s).

The allowed doppler strings and definition are described in function summary.

The shape argument is optional. If your Coordinate System from an image, then assign the image shape to this argument. It is used only when making mixed (pixel/world) conversions for Direction Coordinates to resolve ambiguity.

The example will make the use of this function clear.

Example

- cs := coordsys(direction=T, spectral=T)    # 3 axes
-
- cout := cs.convert (coordin=[10,20,30],
                      absin=[T,T,T],
                      unitsin="pix pix pix",
                      absout=[T,F,T],
                      dopplerout='optical',
                      unitsout="pix arcsec km/s");
-
- print 'cout=', cout
[10 1140.0058 1134.82336]

In this example we convert from a vector of absolute pixels to a mixture of pixel/world and abs/rel.