for CTL = we cannot output the CTL until we actually plot else the
prs_vmin prs_vmax etc are not defined these are the hvmin hvmax

----
6 SEPT 05 -   idea set up an array for the 
	P Refr T0 p			10
	S Refr T0 p			10
	P Refl Mult  T0 p**2		10x10
	S Refl Mult  T0 p**2		10x10
then output at the end of the plot

----
22 SEP 05
	augment ginfo  or perhaps add a gcontrol
to
	1. indicate whether plotxvig.c should call show_menu
		since for this program we turn that off - this is 
		a gframe call -  unless I do the following in 
		plotxvig.c

		If gframe is called and we did not set initialize
		the gframe(2)  or dv_erase(2) will then set a flag that
		says no Quit or Next menu - so we need  two flags

		current argument of dv_erase which is initialized
		initialization flag

		static int initialized = NO;
		static int showmenu = YES;

int dv_erase
		if(initialized == YES) then permit an actual erase
		else just save the parameter showmenu = YES or NO
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For the hyperbola, I could just position the cursor in the 3 quadrant of the
display area and use that to control the hyperbola

I will also need to tell the underlying routine where the origin of the user
x-t space is in the screen space


