FUNCTION read_real, unit, offset
;
; Reads one line from the file opened on 'unit'.
; Extracts the first real number found after skipping the first
; 'offset' characters.
;
; Lines beginning with ':' or that have fewer than offset characters
; are ignored.
;
str = ''
READF,unit, str
; Skip lines beginning with ";" or that are too short
WHILE((STRMID(str,0,1) EQ ";") OR (STRLEN(str) LE offset))  $
   DO READF,unit,str
s = STRMID(str,offset,STRLEN(str)-offset)
READS,s, x
RETURN, x
end