return multiple output variables from Matlab function

Question

Lets say I have a function:

function [ A, B, C ] = test(x, y, z)
    A=2*x;
    B=2*y;
    C=2*z;
end

When you press run, Matlab returns on

Answer 1

Some options:

Add a parameter to specify verbose output the console but set it to false by default:

function [ A, B, C ] = test(x, y, z, verbose)

   if nargin = 3
       verbose = false;
   end;

   A=2*x;
   B=2*y;
   C=2*z;

   if verbose
       fprintf('A = %f\nB = %f\nC = %f', A, B, C);
   end;

end

or combine them into one output:

function output = test(x, y, z)

   A=2*x;
   B=2*y;
   C=2*z;

   output = [A, B, C]; %// Or {A;B;C} if they're not going to be the same size, but then it won't display anyway

end

or if you really really want to I guess you could write a wrapper function that you call on your function and it displays all three for you that you could use generically on any function. But that hardly seems worthwhile.

Answer 2

MATLAB will automatically ouput the variables/expressions those are not end with a ';'.

So if you just need to display all these values, the simplest way will be:

function [ A, B, C ] = test(x, y, z)
    A=2*x    % no ';' will print A's value automatically
    B=2*y    % no ';' will print B's value automatically
    C=2*z    % no ';' will print C's value automatically
end

Answer 3

Another option is to use assignin to automatically save an output argument to the workspace

function [ A, B, C ] = test(x, y, z)
    A=2*x;
    B=2*y;
    C=2*z;

    assignin('base', 'A', A);
    assignin('base', 'B', B);
    assignin('base', 'C', C);      
end

'base' is the name of the main workspace used when you call variables from the command window.

This way you can type test(x,y,z) into the workspace without the [A,B,C] = part and it will still give you all the values.

The benefit of this over combing A, B and C into one output is that you will still have 3 seperate variables saved in your workspace. This is useful if A, B and C are arrays or cells. A disadvantage of this method is that if you use this function inside another function it will still only use the value of A. For example: length(test(x,y,z)) will just give the length of A.

Answer 4

Matlab function outputs are in cell format, so you can define a cell data with the size same as the function output and use it as a single variable to store all the outputs in a more structured way :)

a = cell{3, 1};
[a{:}] = test(x, y, z);
A = a{1};
B = a{2};
C = a{3};