NAME:
	eclipsed_area
 PURPOSE:
	Calculates fraction of solar disk eclipsed by Moon or Earth
 CATEGORY:
	gen/idl/toolbox
 CALLING SEQUENCE:
	FUNCTION eclipsed_area, loc_sun, loc_em, $
	    degrees	= degrees   , $
	    elo 	= elo	    , $
	    ut		= ut	    , $
	    plotc	= plotc     , $
	    earth	= earth     , $
	    radius	= radius    , $
	    silent	= silent    , $
	    _extra	= _extra
 INPUTS:
	loc_sun 	array[3,n] or array[3,2,n]; type: float
			    if array[3,n]; location of Sun in spherical coordinates
				(RA,dec,distance, or long, lat, distance)
			    if array[3,2,n] then array[3,0,*] specifies the location
				of the Sun and array[3,1,*] specifies the location
				of the Moon or Earth. In this case loc_em is ignored.
	loc_em		array[3,n]; type: float
			    location of Earth or Moon in same coordinates as for the Sun.
 OPTIONAL INPUT PARAMETERS:
	/degrees	if set, all angles are in degrees (default: radians)
	/plotc		if set, then results are plotted
			    (angular separation of Sun and Moon or Earth, and fraction of
			    disk eclipsed).
	ut=ut		array[*]; type: structure
			    time structure used to plot a time axis (only used
			    if /plotc is set).
 OUTPUTS:
	area		array[n]; type: float
			    fraction of solar disk eclipsed by Moon or Earth.
 OPTIONAL OUTPUT PARAMETERS:
	elo		array[*]; type: float
			    angular distance between Sun and Moon or Earth
 INCLUDE:
	@compile_opt.pro
 CALLS: ***
	BadValue, InitVar, IsTime, IsType, PlotCurve, SyncArgs, ToDegrees, ToRadians
	sphere_distance
 CALLED BY:
	smei_frm_cvhdr, smei_frm_eclipse
 PROCEDURE:
 MODIFICATION HISTORY:
	OCT-2004, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	env_slashes
 PURPOSE:
	Fixes environment variables on Windows
 CATEGORY:
	gen/idl/environment
 CALLING SEQUENCE:
	PRO env_slashes
 INPUTS:
	(from Windows by retrieving results of spawning
	the DOS 'set' command).
 OUTPUTS:
	(modified env variables)
 INCLUDE:
	@compile_opt.pro	; On error, return to caller
 CALLS: ***
	FILEPATH, txt_read
 PROCEDURE:
	On Windows SSW sets up environment variables with a mix
	of back- and forward slashes. This causes problems for e.g.
	the IDL dialog_pickfile procedure.
	This procedure runs through all env variables and changes
	forward slashes to backward slashes. Only env variables of
	the form SSW_*_INSTR are not modified.
 MODIFICATION HISTORY:
	FEB-2002, Paul Hick (UCSD/CASS; pphick@ucsd.edu)

 NAME:
	EqKepler
 PURPOSE:
	Kepler's equation is used in the determination of orbital positions.
	It gives the relation between mean and eccentric anomaly (for given
	orbit eccentricity).
 CATEGORY:
	smei/gen/idl/ephem
 CALLING SEQUENCE:
	F = EqKepler(E,arg)
 INPUTS:
	E	scalar; type: float
		    eccentric anomaly (radians)
	arg	array[2], type: float
		    arg[0]  mean anomaly      (radians)
		    arg[1]  orbit ellipticity (eccentricity)
 OUTPUTS:
	EqKepler    fnc value
 EXTERNAL BY:
	KeplerOrbit
 PROCEDURE:
	The eccentric anomaly is the root of Kepler's equation:
	EqKepler = X-arg[1]*sin(X)-arg[0] = 0
	See O. Montenbruck, "Practical Ephemeris Calculations", Springer
	(1989), par. 3.1.1.4, p. 44
 MODIFICATION HISTORY:
	1990, Paul Hick (UCSD)

 NAME:
	EulerRotate
 PURPOSE:
	Calculate spherical angles in rotated coordinate system
 CATEGORY:
	gen/idl/toolbox/math
 CALLING SEQUENCE:
	FUNCTION EulerRotate, ABG, In, In1, In2, degrees=Degrees, rectangular=Rectangular
 INPUTS:
	ABG	    array[3] or multi-dimensional array[3,..] with first dimension of 3
			elements. If multi-dimensional, then:
			1. either the array structure, except for the 1st dimension, is the same
			   as for In. Each position in In is rotated using the matching ABG set.
			2. or In is only 1-dimensional i.e. contains only one position. Then
			   each ABG combination is applied to this one position.
			Euler angles [A, B, G]
			A	phase angle of the pole Z(new) in old coordinate system
			B	polar angle of the pole Z(new) in old coordinate system
			G	phase angle of X(new) in coordinate system (2)

	/rectangular NOT SET:
	    In		any multi-dimensional array with first dimension of 2 or 3 elements.
			array[0,..] is the longitude and array[1,..] the latitude;
			array[3,..] (usually the radial distance) is not modified.
	/rectangular SET:
	    In		array[3,..], any multi-dimensional array with array[i,..] (i=0,2)
			the x,y and z-components
 OPTIONAL INPUTS:
	/rectangular	if set, the input array In is interpreted as vectors in rectangular
			coordinates.
			if not set, the input array In is assumed to be in spherical coordinates
			(longitude, latitude, radial distance).
	/degrees	if set, input and output is in degrees
 OUTPUTS:
	/rectangular NOT SET:
			double array with same structure as input array In
			array[0:1,..] are longitude and latitude in new coordinate system
			(0<=Lng<360, -90<=Lat<=90)
	/rectangular SET:
			array[3,..] with same structure as input array In
			x,y,z coordinates in new coordinate system
 INCLUDE:
	@compile_opt.pro			; On error, return to caller
 CALLS: ***
	CvT3d, SubArray, SuperArray, SyncDims, ToRadians
 CALLED BY:
	CvPrecess, CvSky, FishEye, HammerAitoff, KeplerOrbit, MercatorProj, PlotCoronagraph
	PlotEarthSkymap, PlotPlanarCut, RemoteView_CMEDensity, RemoteView_Init_FOV
	RemoteView_StereoStates, RotationMeasure, ThomsonLOSDensity, qvu_draw
	smei_star_stdmaps, smei_zld_dumbbell, vu_coronagraph, vu_elotime, vu_linecut
	vu_planarcut, vu_spherecut
 PROCEDURE:
 >	/rectangular NOT SET:
	Given longitude (phase angle) and latitude (90-polar angle) of a point
	in some coordinate system [axes: X(old),Y(old),Z(old)], angles are
	calculated in the new coordinate system [axes: X(new),Y(new),Z(new)]
	rotated with respect to the original one over the Euler angles Alfa,
	Beta, Gamma.
	The rotation from old to new system is realized by
	(1) rotation around Z(old) over Alfa  ---> X(1),Y(1),Z(1)=Z(old)
	(2) rotation around Y(1)   over Beta  ---> X(2),Y(2)=Y(1),Z(2)=Z(new)
	(3) rotation around Z(new) over Gamma ---> X(new),Y(new),Z(new).
 >	/rectangular SET:
	The 3D rotation !p.t is used do do the transformation.
 MODIFICATION HISTORY:
	1989, Paul Hick (MPAE,UCSD)
	FEB-1998, Paul Hick (UCSD/CASS), added call to cvt3d to handle conversion
	    of rectangular coordinates
	JUN-2000, Paul Hick (UCSD/CASS), added option to rotate
	    single position using multiple Euler angle combinations.
	SEP-2001, Paul Hick (UCSD/CASS),
	    removed a restriction on ABG for a transformation of rectangular
	    coordinates. Only one set of Euler angles was allowed. Now separate
	    Euler angles can be specified for each vector in 'In'; these are
	    processed using an explicit do-loop).
	AUG-2004, Paul Hick (UCSD/CASS)
	    For rotations of spherical coordinates (/Rectangular NOT set) a safety
	    check cos(angle) > (-1) made bad coordinate values disappear
	    (!values.f_nan > 1 returns 1, while !values.f_nan < 1 returns !values.f_nan).
	    The safety check now explicitly checks for bad values, so they don't
	    get lost.
	DEC-2005, Paul Hick (UCSD/CASS, pphick@ucsd.edu)
	    Bug fix. When 1-element arrays are input at In and In1, the output would
	    be a scalar. The output should always have the same structure as the input.