idlastro / Math and Statistics: SUNSYMBOL

[Source code]

NAME
SUNSYMBOL
PURPOSE
Return the Sun symbol as a subscripted postscript character string
EXPLANATION
Returns the Sun symbol (circle with a dot in the middle) as a 
(subscripted) postscript character string.    Needed because although 
the Sun symbol  is available using the vector fonts as the string 
'!9n', it is not in the standard postscript set.   
CALLING SEQUENCE
result = SUNSYMBOL([FONT= ])
INPUTS
None
OPTIONAL INPUT KEYWORDS
font = scalar font graphics keyword (-1,0 or 1) for text.   Note that
       this keyword is useful for printing text with XYOUTS but *not*
       e.g. the XTIT keyword to PLOT where the font call to PLOT takes
       precedence.
OUTPUTS
result - a scalar string representing the Sun symbol.   A different
        string is output depending (1) the device is postscript and
        hardware fonts are used (!P.FONT=0), (2) vector fonts are used,
        or (3) hardware fonts are used on a non-postscript device.
        For case (3), SUNSYMBOL simply outputs the 3 character string
        'Sun'
EXAMPLE
To make the X-axis of a plot read  M/M_Sun
IDL>  cgplot,indgen(10),xtit = 'M / M' + sunsymbol()
RESTRICTIONS
(1) The postscript output does not have the dot perfectly centered in 
        the circle.   For a better symbol, consider postprocessing with
       psfrag (see http://www.astrobetter.com/idl-psfrag/ ).
(2) SUNSYMBOL() includes subscript output positioning commands in the 
        output string.
3) For true-type fonts(Font=1) and IDL Versions prior to V8.2,
   you must first use the SET_FONT keyword to Device to use a font
   that includes the Sun Symbol, e.g. "arial Unicode MS" or
   the Apple Symbols font.
   http://www.idlcoyote.com/misc_tips/sun_symbol.html
   In V8.2 and later, SUNSYMBOL() will automatically convert to the
   DejaVuSans font to create a Sun symbol (and then return to the 
   input font).
4) Also look at CGSYMBOL http://www.idlcoyote.com/programs/cgsymbol.pro
   which includes 'sun' as one if the symbols.
REVISION HISTORY
Written,  W. Landsman,    HSTX          April, 1997
llow font keyword to be passed.  T. Robishaw Apr. 2006
ince IDL8.2 a Sun symbol is available for true-type fonts Feb 2013