Collect outputs from varargout

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Matthew
Matthew on 6 Mar 2012
I am writing some code that utilizes heavy use of varargout. I am running into a problem with using functions that return variable arguments from within functions that return variable arguments. To illustrate this, I made a simple example.
function varargout = myfunc(varargin)
% myfunc
% Adds one and divides by two to each input argument
% Example usage:
% [A,B,C] = myfunc(1,2,3);
% Result:
% A = 1;
% B = 1.5;
% C = 2;
% Create output string for use in eval statement
% depending on number of inputs, makes something like this:
% [temp_var{1}, temp_var{2}, temp_var{3}]
output_str = '[';
for i = 1:length(varargin)
output_str = [output_str 'temp_var{' num2str(i) '}'];
if ~(i==length(varargin))
output_str = [output_str ', '];
end
end
output_str = [output_str ']'];
% Add one to each input then divide by 2
for i = 1:length(varargin)
eval([output_str ' = add_one(varargin{:});']);
varargout{i} = temp_var{i}/2;
end
end
function varargout = add_one(varargin)
% add_one
% Adds one to each input argument
% Example usage:
% [A,B,C] = add_one(1,2,3);
% Result:
% A = 2;
% B = 3;
% C = 4;
% Add one to each input
for i = 1:length(varargin)
varargout{i} = varargin{i} + 1;
end
end
I would like to be able to collect all of the outputs from the add_one function into a single cell array without using the eval statement with the appropriate number of output arguments as I did in the example above. Does anyone have a better way to do this without modifyinfg the add_one function?
  2 Comments
Oleg Komarov
Oleg Komarov on 6 Mar 2012
Please avoid eval: http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F
Matthew
Matthew on 6 Mar 2012
Right. That's why I'm asking for a better way to do this.

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Answers (1)

Oleg Komarov
Oleg Komarov on 6 Mar 2012
I think you miss the point of varargout:
This does exctly the same, avoiding obscure eval construction:
function varargout = myfunc(varargin)
varargout = cellfun(@(x) (x+1)/2,varargin,'un',0);
end

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