nargout

In a file named subtract.m, create a function that calculates a second return value, absdif, only if requested.

type subtract.m

function [dif,absdif] = subtract(y,x)
    dif = y-x;
    if nargout > 1
        disp('Calculating absolute value')
        absdif = abs(dif);
    end
end

At the command prompt, call the subtract function with one return value.

diff = subtract(42,13)

diff = 
29

Call the subtract function again with two return values.

[dif,absdif] = subtract(2,5)

Calculating absolute value

dif = 
-3

absdif = 
3

Determine how many outputs a function can return.

The function subtract created in the previous example has two outputs in its declaration statement (dif and absdif).

fun = @subtract;
nargout(fun)

ans = 
2

Determine how many outputs a function that uses varargout can return.

In a file named mySize.m, create a function that returns a vector of dimensions from the size function and the individual dimensions using varargout.

type mySize.m

function [sizeVector,varargout] = mySize(x)
    sizeVector = size(x);
    varargout = cell(1,nargout-1);
    for k = 1:length(varargout)
        varargout{k} = sizeVector(k);
    end
end

Query how many outputs mySize can return.

fun = 'mySize';
nargout(fun)

ans = 
-2

The minus sign indicates that the second output is varargout. The mySize function can return an indeterminate number of additional outputs.