{Program to display an object's position in real time}

{Set the delimiter to "%" so we can use "," in prompts}
set_delimiter(%)

{On first pass, get the name of the object etc.}
if (s1=.)
   set_string(s1%Sun)
   display_title(+++ Real-time Positions +++)
   write_string(Possible objects are:)
   new_line
   write_string(Sun, Moon, name of a planet, parabolic or elliptical)
   new_line
   new_line
   ask_for_string(Name of object [choose one of the above]%s1)
   set_string(s2%true)
   ask_for_string(Coordinates: true, apparent, or topocentric%s2)
   set_coordinates_type(s2)
   set_string(s3%5)
   ask_for_string(Time step between updates%s3)
   new_line
end_if

{Use the character variable c1 for both coordinate type and error}
set_character(c1%N)

{Check that the calculation is allowed}
if (s1=sun)
   set_character(c1%s)
end_if
if (s1=moon)
   set_character(c1%m)
end_if
if (s1=mercury)
   set_character(c1%p)
end_if
if (s1=venus)
   set_character(c1%p)
end_if
if (s1=mars)
   set_character(c1%p)
end_if
if (s1=jupiter)
   set_character(c1%p)
end_if
if (s1=saturn)
   set_character(c1%p)
end_if
if (s1=uranus)
   set_character(c1%p)
end_if
if (s1=neptune)
   set_character(c1%p)
end_if
if (s1=elliptical)
   set_character(c1%o)
end_if
if (s1=parabolic)
   set_character(c1%o)
end_if

{Raise an objection if the requested calculation is illegal...}
if (c1=N)
   set_normal_text(12)
   new_line
   write_string(   +++ )
   write_string(s1)
   write_string( is not an allowed calculation type)
   new_line
   new_line
   set_normal_text(7)

{...wait for a response}
   pause

{...and reset s1 to its default condition}
   set_string(s1%.)

end_if

{If the calculation is allowed...}
if (c1!N)

{...carry out the calculation}
   find_position(s1)

{...convert to az/alt}
   convert_coordinates(c1%a)

{...clear the screen and put up a title}
   set_normal_text(15)
   display_title(s1)
   set_normal_text(7)

{...display the time and date}
   set_decimal_places(0)
   display_date(calendar)
   display_time(solar)
   new_line

{...display the result}
   write_string(Coordinate type: )
   write_string(s2)
   new_line
   set_normal_text(14)
   display_coordinates(a)
   set_normal_text(7)
   new_line

{...and wait for the clock}
   wait_time_step(s3)

end_if

{Finally repeat the whole lot with no questions asked}
repeat