Too many output arguments error in my code

I have the following code, I am trying to get all of the wavelet approximations out (it works fine with details, but not approximations).

I know what the error means, I just can't figure out how it applies in my code.

GRACE = load ('GRACE.txt')

ncol = size(GRACE,2);
for k = 1:ncol
    [c,l] = wavedec(GRACE(:,k),6,'dmey');
cA6 = appcoef(c,l,'dmey',6);
[cD1,cD2,cD3,cD4,cD5,cD6] = appcoef(c,l,[1,2,3,4,5,6]);

   D = [];
      D(:,6) = wrcoef('d',c,l,'dmey',6);
      D(:,5) = wrcoef('d',c,l,'dmey',5);
      D(:,4) = wrcoef('d',c,l,'dmey',4);
      D(:,3) = wrcoef('d',c,l,'dmey',3);
      D(:,2) = wrcoef('d',c,l,'dmey',2);
      D(:,1) = wrcoef('d',c,l,'dmey',1);
      filename = sprintf('%s_%04f.txt', 'GRACE_APROXIMATIONS', k)
      csvwrite(filename,D)

end

Any help would be greatly appreciated

[Stephen23]

Related to this question by the same OP:

http://www.mathworks.com/matlabcentral/answers/218021-looping-through-every-column-and-saving-output

Answer 1

[Walter Roberson]

appcoef() only ever returns one variable. You are trying to get it to return 6.

If you are not passing a string representing the wavelet name, then you should be using either 4 or 5 arguments, with the 3rd and 4th being filters. Your [1,2,3,4,5,6] is being interpreted as a filter.

You cannot pass in a list of levels and get one output variable for each.

[Robert]

Ok thanks, i didn't know that (new to matlab)

Any recommendation on how I can alter the code so it gives approximations at 6 levels?

[Walter Roberson]

You do them one at a time. Possibly in a loop.

[Robert]

So something like this? This is my best interpretation of what you suggest, Still I get the same error, am I on the right path?

GRACE = load ('GRACE.txt')

ncol = size(GRACE,2);
for k = 1:ncol
    [c,l] = wavedec(GRACE(:,k),6,'dmey');
cA1 = appcoef(c,l,'dmey',1);
cA2 = appcoef(c,l,'dmey',2);
cA3 = appcoef(c,l,'dmey',3);
cA4 = appcoef(c,l,'dmey',4);
cA5 = appcoef(c,l,'dmey',5);
cA6 = appcoef(c,l,'dmey',6);
[cA1,cA2,cA3,cA4,cA5,cA6] = appcoef(c,l,[1,2,3,4,5,6]);

   D = [];
      D(:,6) = wrcoef('d',c,l,'dmey',6);
      D(:,5) = wrcoef('d',c,l,'dmey',5);
      D(:,4) = wrcoef('d',c,l,'dmey',4);
      D(:,3) = wrcoef('d',c,l,'dmey',3);
      D(:,2) = wrcoef('d',c,l,'dmey',2);
      D(:,1) = wrcoef('d',c,l,'dmey',1);
      filename = sprintf('%s_%04f.txt', 'GRACE_APROXIMATIONS', k)
      csvwrite(filename,D)

end

    if true
      % code
    end

[Stephen23]

@Robert: the appcoef documentation shows these syntaxes:

A = appcoef(C,L,'wname',N)
A = appcoef(C,L,'wname')
A = appcoef(C,L,Lo_R,Hi_R)
A = appcoef(C,L,Lo_R,Hi_R,N)

Count the outputs: each syntax shows exactly one output. You wrote this:

[cA1,cA2,cA3,cA4,cA5,cA6] = appcoef(c,l,[1,2,3,4,5,6]);

Count the outputs: there are six of them. The error message is telling you that you have too many outputs for this function: appcoef provides only one output.

To fix this you have to call appcoef in a loop, as Walter Roberson wrote.