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    Re: Round-off
    From: Lu Abel
    Date: 2009 May 17, 17:28 -0700

    In most engineering schools students are taught to carry out
    calculations to at least one more digit of accuracy that is desired in
    the final answer and only round at the very end.
    I also have to wonder about "0.1' of arc and 0.1 deg of azimuth"   0.1
    degree of azimuth is exceedingly hard to measure either with a compass
    or to plot on a chart, whereas 0.1' of arc is 0.1 nm, easily discernible
    on most mid- to large-scale charts or on a plotting sheet used to reduce
    two LOPs to a L/Lo of position.
    Anabasis wrote:
    > I've never heard of rounding to the nearest whole minute during
    > reduction.  That doesn't seem too wise to me.  What I was taught from
    > all sources is to carry 1 decimal point at all times (0.1' of arc and
    > 0.1 deg in azimuth).  This was for all tabular reduction.  When I work
    > with formulae, I am carrying 13 places in my calculator and then round
    > to the nearest 10th when I am finished.
    > Using my tools on paper charts/plotting sheets for Celnav, I am
    > usually interpolating by eye, divisions less than 1 minute of lat or
    > long and within 1 degree of azimuth.  Better precision in the
    > reduction process is generally wasted during the plotting process in
    > practice.
    > If you are using computers to plot, its a whole other story in both
    > reduction and plotting precision.
    > Jeremy
    > >
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