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    Re: learning sight reduction
    From: Bill B
    Date: 2006 May 3, 21:41 -0500

    Alex wrote:

    > But still I think the word "challenge"  does not necessary imply
    > a duel. We (mathematicians) say "a challenging problem", for example,
    > about a problem which attracts us.

    Adjective vs. verb ;-)  "I challenge you to..." vs "It is a challenge

    In reality I do use a calculator quite often even when practicing 229.  I
    use it at least for v, d, time-to-arc, and final d correction to tabular
    data.  Sometimes for interpolation of Z.

    With the TI-XA30 (which I consider to be more intuitive for me than the
    Casio, especially for one-variable statistics) I can generally determine Hc
    and Zn in 3 to 3 1/2 minutes once time, AP, GHA, SHA, declination, d and v
    have been established.

    General method for standard formulas/sun.

    Decimal time increment in memory 1 (M1)
    GHA in memory 2 (M2)
    Declination in memory 3 (M3)

    M1 * 15 + M2, store M2
    M1 * d +/- M3, store M3
    M2 +/- AP lon, store M2
    Decimal lat, store M1

    (Actually I just use the sum, 2nd, memory-number sequence to add or subtract
    to the to the registers)  Of course there are 2 extra keystrokes to convert
    each set of dd/mm/ss to decimal degrees.

    For Hc
    sin M1 * sin M3 =, + (cos M1 * cos M2 * cos M3) =
    Then 2nd sin (store in M2)

    For Z
    sin M3 - (sin M1 * sin M2)=, / (cos M1 * cos M2)=
    2nd cos
    If sin LHA (M2) positive, subtract Z from 360 for Zn
    (store in M1)

    In practice I run Hc at least twice before storing in M2 (little keys are
    easy to mispunch).  If the first two do not agree, I run it a third time.

    Same with Z.

    Zn is stored in M1, so I have Zn recorded in M1 and Hc recorded in M2.

    When finished I can recall M1 and M2 and write it down.

    I do like the ability to enter dd/mm.m in the Casio.


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