Demonstrate earth nutation, precession and rotation.

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See also Plot2D, Date2JD, JD2T, TruEarth
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Contents

Start date
Look over 10 years by 25 day intervals
Plot the north pole
Look over 1000 years by 10 year intervals
Plot the z component of the north pole

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%   Copyright (c) 1994 Princeton Satellite Systems, Inc.
%   All rights reserved.
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%   Since version 1.
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Start date

%-----------
jD = Date2JD([1995 1 1 0 0 0]);

Look over 10 years by 25 day intervals

%----------------------------------------
x  = zeros(3,146);

for k = 1:146,
  c      = TruEarth(JD2T(jD+25*(k-1)));
  x(:,k) = c(:,3);
end
time = (0:145)*25/365.25 + 1995;

Plot the north pole

%--------------------
Plot2D(time,[x(1:2,:);1-x(3,:)],'Time (years)',['x  ','y  ','1-z'],'North Pole Short Term');

Look over 1000 years by 10 year intervals

%----------------------------------------
x  = zeros(1,100);
dD = 3652.50;

for k = 1:100
  c    = TruEarth( JD2T( jD+dD*(k-1) ) );
  x(k) = c(3,3);
end
time = (0:99)*dD/365.25 + 1995;

Plot the z component of the north pole

%---------------------------------------
Plot2D(time,1-x,'Time (year)','1-z','North Pole Z Component Long Term');


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