~TOP
>Spheric 1.26 ¸1995 by J.A.Wrotniak

  To choose a topic from the list below,
type its  first letter or two  and press
Enter.

>Topics

   * calculations    * input formats
   * database        * keyboard
   * Earth models    * menu
   * exit            * prompts
   * finding fixes   * settings
                     * registration
?
!CALCULATIONS
>CALCULATIONS
  These are performed from the CAL menu:
[FFd] - distance between two fixes
[Azi] - azimuth from a fix to another
[Mid] - midpoint between two fixes
[Aim] - fix at an azimuth and distance
[FAd] - fix-to-arc distance
[Prj] - projection of a fix on an arc
[AAd] - arc-to-arc distance
[Int] - intersection of two arcs/circles
>Topics
   * aiming        * intersection   
   * azimuth       * midpoint
   * distance      * projection
?
#DISTANCE
>DISTANCE COMPUTATION
  Distance-computing operations from the
CAL menu include:
[FFd] - distance between two fixes
[FAd] - distances  from a fix to a great
        arc and to the arc's circle
[AAd] - distance between two great arcs
 Depending on the [Set|Uni] setting, the
results will be in kilometers (km), U.S.
miles (mi), nautical miles (nm), degrees
of arc (arcø) or minutes of arc (arc').
>Topics
  * AA distance      * FF distance
  * FA distance
?
$FF distance
>DISTANCE BETWEEN FIXES

  [Cal|FFd]  finds the  distance between
two fixes, specified by their names.

  Entering a  "+" and  a single fix name
will append that fix to the previous FFd
calculation,  computing the total length
of an arc sequence.
.
$FA distance
>FIX TO ARC DISTANCE
 [Cal|FAd] prompts for a fix and a great
arc, then finds two distance values:
- the "circle distance"  from the fix to
  the arc's  great  circle  (i.e. to the
  projection of the fix on that circle)
- the "arc distance" from the fix to the
  closest point on the arc itself.
  Both results are identical if the pro-
jection  falls within  the arc; in  this
case a "*" will follow the result.
  Otherwise a "-"  or  "+"  will follow,
denoting  that the closest  point is the
arc's start or end, respectively.
.
$AA distance
>DISTANCE BETWEEN GREAT ARCS

  [Cal|AAd]  prompts for  two great arcs
(specified by  names of their  start and
end fixes), then computes  the  distance
between them, i.e. the shortest distance
between  any point on one arc and any on
the other.

  If the  arcs  intersect  (within  both
lengths) or overlap,  the result will be
zero.
.
#AIMING
>AIMING BY RANGE AND BEARING

 [Cal|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 (optional) which  will be used to
  add the result to the fix database.

- Azimuth is measured clockwise from the
  North.
.
#AZIMUTH
>AZIMUTH

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

- Results are shown in decimal degrees

- Azimuth is measured clockwise from the
  North; values range from -180ø to 180ø
  or from 0ø to 360ø (see "Settings")
.
#MIDPOINT
>MIDPOINT

 [Cal|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
  (optional) which will  be then used to
  add the midpoint to the fix database.
.
#PROJECTION
>PROJECTING A FIX ON A GREAT CIRCLE
  [Cal|Prj]  finds  the  projection of a
fix  on an arc's  great circle.  Thia is
the circle's point closest to the fix.
- The distance  between the original fix
  and  its  projection  can  be computed
  with [Cal|FAd] (see "Distance").
- A "*","-" or "+" mark after the result
  will show  whether the  projection be-
  longs to the arc, precedes  or follows
  it, respectively.
- You  will be  asked for a new fix name
  which, if given,  will be used  to add
  the projection to the fix database.
.
#INTERSECTION
>INTERSECTION OF TWO ARCS
  [Cal|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.
.
!DATABASE
>DATABASE OPERATIONS
  These are available from the DAT menu:
[Loa] - load fixes from file  (append or
        replace)
[Sav] - save fixes to a file
[Mem] - memory status (max.no.of fixes)
[Nam] - sort fixes by name
[Cat] - sort fixes by category
[Prx] - sort fixes by proximity  to  the
        currently selected fix
[Clr] - clear fixes  and/or  history (as
        chosen from the CLR menu)
>Topics
 * disk operations
?
#DISK OPERATIONS
>DISK OPERATIONS
  Disk files  with fixes  must  have the
FIX extenstion, e.g. TEST.FIX; they also
have to reside in the same directory  as
the program.
  When loading or saving fixes,  Spheric
will prompt you for a file name. The FIX
extension can be omitted.
  Upon prompt,  pressing  the down-arrow
will scroll  through all  .FIX  files in
the program directory; the up-arrow will
restart the scrolling.
  Pressing  the Tab key  will recall the
last entry. Esc clears the input line.
.
!FINDING
>FINDING FIXES

- To find a fix,  start typing its name.
  As soon as you stop typing (one second
  break),  Spheric  will search  for the
  first fix matching the pattern.

- To find a fix  by its  category,  type
  the category preceded with a comma.

- Pressing  the  Tab key  will  find the
  next fix matching the pattern.
.
!EARTH
>EARTH MODELS
  Two Earth models are provided:
(E) Elliptical Earth (GRS 1980) with
    - Polar Radius = 6356.7523 km
    - Equatorial Radius = 6378.1370 km
(S) Spherical Earth, averaged to
    - Mean Radius = 6367.4357 km
  In both  cases  the  calculations  are
done on a sphere, except that in (E) the
geographic  latitude is  first converted
into geocentric  (the  opposite  happens
when results are displayed).
  [Note: the "Geo" results in  [Cal|FFd]
and [Cal|Azi] always use an ellipsoid.]
.
!EXIT
>EXITING THE PROGRAM

 To terminate the program, press [Exit].
You will be then given an option to save
a file  SPH.ENV with all  current fixes,
history and settings.

 This file will be read  by the  program
the  next time you  run it,  so that you
can resume where you left before.

 For fast exit without any prompts, just
press Shift-F10.
.
!KEYBOARD
>KEYBOARD COMMANDS
  With no prompt shown at the bottom:
- ".": show selected fix (full accuracy)
- Enter: edit the selected fix
- Ins: insert new fix (before selected)
- Del: delete the selected fix
- Up, Down: scroll by one fix
- PgUp, PgDn: scroll by page
- Home, End: scroll to top, bottom
- Bsp: delete history entry
- Left, Right: scroll history
- Ctrl-Left,-Right: history top, bottom
- Space - go to Cal or Set Menu
- Tab - repeat last fix search
.
!MENU
>MENU COMMANDS (TOP)
  The top function key menu includes the
following operations:

[Set]  - switch to the Settings Menu
[Cal]  - switch to the Calculations Menu
[Dat]  - switch to the Data Menu
[Exit] - exit the program
  In all menus the F1 key is marked with
the menu name  (here: TOP);  pressing it
brings this help.
  For the explanation of the other menus
see under "Settings", "Calculations" and
"Database".
.
!PROMPTS
>PROMPTS
  Prompts  at the bottom  of the  screen
ask for one of the following:
- A simple Yes/No answer: Y or N.
- Fix  name(s)  (changed to  uppercase).
  Use Tab for name  completion;  up/down
  arrows to recall recent inputs.
- Latitude  and longitude  in any of the
  formats recognized by Spheric (see
  "Input Formats"
- Distance (in units as indicated).
- Azimuth (in decimals or in ø and ').
  At any prompt  Escape clears  input or
cancels the whole operation.
.
!INPUT FORMATS
>INPUT FORMATS
  The following  latitude and  longitude
formats are recognized  on input (either
at a prompt of from a data file):

- DMS:      23ø02'58"S 125ø33'E
- Infix:    23S0258    125E33    
- Decimal:  23.0494S   125.5500E

  For DMS and Decimal formats, the alpha
character can be replaced with a leading
"+" or "-" (as defined by [Set|+/-]).
  The  minutes field  cannot be skipped,
if the seconds value is non-zero.
.
!SETTINGS
>SETTINGS
  Some  program settings  are accessible
from the SET menu:
[Uni] - set distance units
[Acc] - toggle distance and azimuth dis-
        play accuracy
[Ang] - set angle (lat/lon) display mode
        (see "Input Formats")
[360] - change azimuth display mode
[+/-] - set default signs of N/S and E/W
[Cat] - enable/disable  category  use in
        the history log
[Snd] - toggle sound on/off
[Ert] - set the Earth model
.
!REGISTRATION
>REGISTRATION AND SUPPORT
  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
.
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