//- v.1.03
 Spheric (c) 1993 by J.A.Wrotniak 

  Chose  from  the available  topics (by
typing in the first few letters):

   * aiming          * intersection
   * azimuth         * keyboard
   * calculations    * menu
   * closest dist.   * midpoint         
   * database        * passing dist.
   * distance        * projection
   * Earth models    * prompts
   * files           * settings
                     * registration
//AIMING
 Aiming by Range and Bearing 

  [Aim]  computes  a new  fix at a given
distance  and azimuth  from a  given fix
(selected  by name).  You will be  asked
for all these three items.

* You  will be also  asked for a new fix
  name  which  will  be used  to add the 
  result to the fix database.

* Azimuth is measured clockwise from the
  North.
//AZIMUTH
 Azimuth 

  [Azi]  computes  the azimuth  from one
fix (selected by name) to another.

* The result  will be  shown  in ø and '
  or in decimals (degrees), depending on
  the current [Ang] setting.

* Spheric measures azimuth from the true
  North , from  -180ø to 180ø,  with "+"
  defined clockwise (East).
//CALCULATIONS
 The Calculations Menu 
 The following operations are accessible
from here:
[Hlp] - call this help
[Dis] - distance between two fixes
[Azi] - azimuth from a fix to another
[Mid] - midpoint between two fixes
[Aim] - fix at a given azimuth and
        distance from another
[Clo] - closest distance (fix-arc)
[Pas] - passing distance (fix-circle)
[Prj] - projection of a fix on an arc
[Int] - intersection of two arcs/circles
[Top] - return to the Top Menu
//CLOSEST
 Closest Distance (Fix to Arc) 

  [Clo] finds the closest distance  from
a fix to an arc.
  The  closest  point on the arc  may be
one of the following:
* The projection of the fix on the arc's
  great  circle  (the  displayed  result
  will be then followed by "*")
* The arc's start (case denoted as "-")
* The arc's end ("+" will be shown).
In the first case, the result is equiva-
lent to  the passing distance,  computed
by [Pas] (see).
//DATABASE
 The Data Menu 

  The following database  operations are
available from this menu:
[Hlp] - call help
[Loa] - load  fixes  from a file (adding
        to the current database)
[Sav] - save  fixes  to  a  file  (local
        directory only, .FIX assumed)
[Srt] - sort fixes by name
[Prx] - sort fixes by proximity to the
        currently selected fix
[Clr] - clear fixes and history
[Top] - go to the Top Menu
 
* See also "Files"
//DISTANCE
 Distance 
  [Dis]  computes  the distance  between
two fixes (selected by names).

* Instead of the first name a "+" can be
  entered.  Spheric  will  then  use the
  second fix from the previous  Distance
  calculation, and add the results.

* Depending  on the  units  currently in
  use,  the result will be in kilometers
  (km),  U.S. miles (mi), nautical miles
  (nm), degrees of arc (arcø) or minutes
  of arc (arc', approx.equal to nm).
//EARTH MODELS
 Earth Models 
  Two Earth models are provided:

(E) Elliptical Earth with
    - Polar Radius = 6356.7523 km
    - Equatorial Radius = 6378.1370 km
(S) Spherical Earth, averaged to
    - Mean Radius = 6367.4357 km

In both cases  all calculations are done
on a sphere, except that in (E) the geo-
graphic latitude is first converted into
geocentric  (the  opposite  happens when
results are displayed).
//FILES
 Files Written and Read by Spheric 
  When [Exit] is pressed,  Spheric saves
a file SPH.ENV with all current data and
settings, then asks for confirmation.
  To exit w/o saving, press Shft-F10.
  SPH.ENV  is read  by the  program when
you run it, so that you can resume where
you left before.
  [Dat|Sav]  saves all fixes  as a plain
text file in the current display format.
When prompted,  enter  file name without
path or extension (.FIX assumed)
  [Dat|Loa]  loads a .FIX file as above,
adding its contents to the current data.
//INTERSECTION
 Intersection of Two Arcs 
  [Int]  finds  the intersection  of two
great arcs (each defined by names of its
two ends, see "Prompts").
  The intersection  may be not "proper",
i.e. it may  be outside of  either arc's
span.  This is shown  by two characters,
one for each arc, which denote:
   "-" - before the arc's start fix,
   "*" - within the arc's length,
   "+" - after the  arc's end fix.
  For improper  cases, out of two possi-
ble  solutions,  Spheric choses  the one
which is closer to the arcs involved.
//KEYBOARD
 Keyboard Commands 
  Available  when  no  prompt  is  being
shown at the bottom (see "Prompts").
* Enter: edit the selected fix
* Ins: insert new fix (before selected)
* Del: delete the selected fix
* Up, Down - scroll by one fix
* Tab, BackTab - scroll by page
* PgUp, PgBot - scroll to top, bottom
* Bsp - delete history entry
* Left, Right - scroll history
* Home, End - history top, bottom
* Space - go to Cal or Set Menu
See also "Menu" for more commands.
//MENU
 Menu Commands 

  The top function key menu includes the
following operations:

[Hlp]  - bring this help
[Set]  - switch to the Settings Menu
[Cal]  - switch to the Calculations Menu
[Dat]  - switch to the Data Menu
[Exit] - exit the program

  For the explanation of the other menus
see under "Settings", "Calculations" and
"Data".
//MIDPOINT
 Midpoint 

  [Mid]  computes  the midpoint  between
two fixes (selected by names).

* A midpoint is defined  as the point on 
  the great arc  connecting  both fixes,
  at the same distance from either.

* You  will be  asked for a new fix name
  which  will  be  then used to  add the 
  midpoint  to the  fix  database.  This
  name can be skipped.
//PASSING
 Passing Distance (Fix to Circle) 

  [Pas] finds the passing  distance from
a fix  to  an arc's  great circle,  i.e.
between   the  fix  and  its  projection
(closest point) on the circle.
* If the projection  does not  belong to
  the arc, a "-" or "+" will  follow the
  result, denoting that the point is be-
  fore the arc's start or after its end,
  respectively.
* If it does, a "*" will be shown.
* The  projection  point  itself  can be
  computed with [Prj] (see "Projection")
//PROJECTION
 Projecting a Fix on a Great Circle 
  [Prj] finds the  projection of a given
fix on an  arc's great circle,  i.e. the
circle's point closest to the fix.
* The distance  between the original fix
  and  its  projection  can  be computed
  with [Pas] (see "Passing").
* A "-", "+" or "*" flag will follow the
  result to show whether the  projection
  belongs to the arc (see "Passing").
* You  will be  asked for a new fix name
  which  will be used to add the projec-
  tion to the fix database.
* See also "Prompts".
//PROMPTS
 Prompts 
  Prompts at the screen bottom ask for
one of the following:
- A simple Yes/No answer: Y or N.
* Fix name(s); will be changed to upper-
  case.  Tab can be  used for  name com-
  pletion or to recall previous input.
* Latitude  and  longitude  in  decimals
  (degrees) or in ø and ' (ALT+d for ø).
  A "-" can be used instead of S or W.
* Distance (in units as indicated).
* Azimuth (in decimals or in ø and ').
At  any  prompt  Escape clears  input or
cancels the whole operation.
//SETTINGS
 The Settings Menu 

  Some  program settings  are accessible
from here:

[Hlp] - call help
[Uni] - set distance units
[Ang] - set angle display mode
[+/-] - set default signs of N/S and E/W
[Com] - toggle comma use in names
[Snd] - toggle sound on/off
[Ert] - set the Earth model
[Top] - go back to the Top Menu
//REGISTRATION
 Support and Registration 
  Spheric is shareware:  if you keep and
use it, send a fee of $30 to the author:
   Dr. J. Andrzej Wrotniak
   2057 Happy Lane
   Crofton, MD 21114-1917
  You will receive an upgrade to the "R"
(registered)  version  on a  3.5"  disk,
with a number of  enhanced  features.

  Comments,  questions,  suggestions and
problem  reports are  welcome and can be
also sent by email:
  GEnie: J.WROTNIAK    CIS: 46511,2552
//-
