(Comp.sys.handhelds)
Item: 315 by fin at norge.unet.umn.edu
Author: Craig A. Finseth
  Subj: HP-48SX Program to Calculate/Show the Phase of the Moon
  Date: Wed Apr 04 1990 16:14 

[Note: See MOON2 for an improved version.  -jkh-]

In order for bugs to depend on the phase of the moon, they must first
be able to find out what the phase of the moon is.  This program
should help.

Note: this program uses a first-order sine approximation.  The correct
expression contains about 30 sine terms.  Still, what you see displayed
corresponds reasonably well with what you see in the sky...

MPHASE  Calculate and show the phase of the moon for the current date/time
MTIME   Calculate and show the moon time string for the current date/time
MFRAC   Calculate the moon phase fraction (0 new moon; .25 first quarter;
        .5 full moon; .75 last quarter)
FLIP    Invert the screen.  Fast, but displays garbage during the flip.
MPLOT   Internal to MPHASE: Plot the crescent
MLINE   Internal to MPHASE: Draw a line of the crescent

Notes:

- If you want to generalize the date/time calculated for, change MFRAC.

- You can omit the flip by removing the call to FLIP from MPHASE.

- The base time for new moon is 12 Jan 1975 at 10:21 am GMT (4:21
  AM CST, which is the figure used in the program).

- The moon cycle is assumed to be 42,532 minutes long.

Checksum: #3794h
Size: 1153.5

Craig A. Finseth              fin@unet.umn.edu [CAF13]
University Networking Services          +1 612 624 3375 desk
University of Minnesota            +1 612 626 1002 FAX
130 Lind Hall, 207 Church St SE, Minneapolis MN 55455-0134, U.S.A.
-------------------------------------------------------------------------------
  Resp: 1 of 1 by prestonb at hpcvra.CV.HP.COM
Author: Preston Brown
  Date: Fri Apr 06 1990 16:49 

If you don't want to glitch the display then change FLIP to:

FLIP
\<< PICT PICT RCL NEG {#0 #0} SWAP REPL \>>

This version is also faster.

Preston
-------------------------------------------------------------------------------
(Feedbackto.hp) Main: r
Item: 16 by _davidmotto at hpcvbbs.UUCP
Author: David G Motto
  Subj: HP-48SX Date command
  Keyw: date hp-48
  Date: Sun Apr 08 1990 05:57 

How come I can't set the "date" on my 48SX to a date in the far
past?  I input the "Moon phase" programs, and I want to see the 
phase of the moon when I was born.  No, it wasn't before Oct 15,
1582!  Where does it say what the range of "date settings" can
be?  Can the "Moon phase" program be rewritten to use previous
dates? (It is in user.programs).
-------------------------------------------------------------------------------
  Resp: 1 of 1 by meghas at hpcvbbs.UUCP
Author: Megha Shyam
  Date: Tue Apr 17 1990 11:00 

   Hello David:

   In the TIME application, you are correct in discovering that you
   set the date of the HP 48SX to any arbitrary date.  In fact there 
   is only a finite range (Jan 1, 1989 to Dec 31, 2088).  This is not
   indicated anywhere in the manual unfortunately.  We had to make some
   choices when working in this area: number of days calculation between
   two given dates does accept a wide range of dates; however to set a 
   date to a given value we had to truncate it to only a 100 year 
   range and we choose the starting point as Jan 1, 1989.  Thus the
   "Moon Phase" program rewrite is very tedious and cumbersome.

   Megha Shyam
   Hewlett-Packard