MATLAB: Debugging

debugging

function E = kepler (e, M)
  % E = kepler(e, M)
  % Solves kepler's equation for E, the eccentric anomoly given
  % e, the orbital eccentricity and M, the mean anomoly. 
  for i = 1:length(M)
  E(i) = fzero(@func, 1);
  end
  function out = func(E)
      out = E - e*sin(E)-M(i);
  end

end

the goal is to solve keplers equation using the zero function but I keep getting Error messages in return

Best Answer

kepler(exp(1),4)
kepler(exp(1),magic(4))

works for me...

Related Solutions

MATLAB: How can we find the non common strings from multiple columns

First lets find the strings that are common to all cell arrays:

listA={'India','Iran','Ireland','Israel','Jordan','Kuwait','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines',};
listB={'Denmark','El Salvador','Gabon','Gambia','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines','Qatar','Rwanda','Saudi Arabia','Senegal','Singapore','Sudan'};
listC={'Kuwait','Lebanon','Lesotho','Nepal','Netherlands','Oman','Sweden','Syria','Tanzania','Turkey','Uruguay'};
%

lists = {listA,listB,listC}; % storing data together makes working with them much simpler.
%
exc = lists{1};
for k = 2:numel(lists)
    exc = intersect(exc,lists{k});
end

giving the strings found in all cell arrays as:

 exc =
    'Lebanon'
    'Lesotho'
    'Nepal'
    'Netherlands'
    'Oman'

Now we can easily get the input cell arrays with the strings from exc removed:

out = cell(size(lists));
for k = 1:numel(lists)
    out{k} = setdiff(lists{k},exc);
end

giving:

>> out{:}
ans = 
    'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines'
ans =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan'
ans =
    'Kuwait' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

And if you want a list of all strings together, excluding those in exc:

uni = {};
for k = 1:numel(lists)
    uni = union(uni,lists{k});
end
uni = setdiff(uni,exc)

gives:

uni =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

MATLAB: How to solve Kepler’s equation for E using fzero

To use fzero, you first need to form an equation with 0 on one side. So this equation:

M = E - e * sin(E)

becomes this equation:

0 = E - e * sin(E) - M

Then set up your known values:

e = something
M = something

Then form a function handle for the equation that you want to be 0 as a function of what you want to solve for, which is E in this case:

kepler_equation = @(E) E - e * sin(E) - M

Then it is just a matter of calling fzero with this function handle and an initial guess. E.g., you could use M as the initial guess. I will leave that part for you to figure out. Look at the doc for fzero to see how to call it.

If you are creating a function that outputs E given e and M, then the outline of that function would be this in a file called Kepler.m:

% E = Kepler(e,M) solves Kepler's equation, E and M are in radians
function E = Kepler(e,M)
% form the function handle here  <-- you insert this code
% call fzero here  <-- you insert this code
return
end

The code you insert above will be based on the advice I gave you above.

Best Answer

Related Solutions

MATLAB: How can we find the non common strings from multiple columns

MATLAB: How to solve Kepler’s equation for E using fzero

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