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coordsys.topixel - Function

	Package	general
	Module	images
	Tool	coordsys

Convert from absolute world to pixel coordinate

Synopsis
topixel(value)

Arguments

value	in	Absolute world coordinate
		Allowed:	Numeric vector, vector of quantities, vector of strings or record
		Default:	Reference value

Returns
Vector of double or fail

Description

This function converts between world (physical) coordinate and absolute pixel coordinate (1-rel).

The world coordinate can be provided in one of four formats via the argument world. These match the output formats of function toworld.

If you supply fewer world values than there are axes in the Coordinate System, your coordinate vector will be padded out with the reference value for the missing axes. Excess values will be silently ignored.

You may supply the world coordinate in all of the formats described in the formatting discussion.

Example

- cs := coordsys(direction=T, spectral=T, stokes="I V", linear=2)
-
- w := cs.toworld([-2,2,1,2,23,24], 'n')
- cs.topixel(w)
[-2 2 1 2 23 24]  
-
- w := cs.toworld([-2,2,1,2,23,24], 'q')
- cs.topixel(w)
[-2 2 1 2 23 24]  
-
- w := cs.toworld([-2,2,1,2,23,24], 'm')
- cs.topixel(w)
[-2 2 1 2 23 24]  
-
- w := cs.toworld([-2,2,1,2,23,24], 's')
- cs.topixel(w)
[-2 2 1 2 23 24]  
-
- w := cs.toworld([-2,2,1,2,23,24], 'mnq')
- cs.topixel(w)                            
[-2 2 1 2 23 24]

Example

- cs := coordsys (stokes="I V", linear=2)
- cs.toworld([1,2,3], 's')
I 1.000000e+00 2.000000e+00 
-
- cs.toworld([1,2,3], 'm')
[stokes=I, linear=[*1=[value=1, unit=km], *2=[value=2, unit=km]]] 
-
- cs.toworld([1,2,3], 'q')
[*1=[value=1, unit=], *2=[value=1, unit=km], *3=[value=2, unit=km]]

Example

- cs := coordsys (spectral=T, linear=1)
- cs.toworld([1,2,3], 'q')
[*1=[value=1.415e+09, unit=Hz], *2=[value=1, unit=km]]