How to write my function output in various form?

Many MATLAB functions have options to spit out various forms of outputs. I have a function spitting out 7 arrays. I would like to use either a single output as a matrix composed of all 7 arrays or arrays by specifying each array by name using something like [~,~, a, b, ~, ~, ~]. Any advice or references?

Some functions with a single output allocate the first output in the list of [,...,], and I would like to get all outputs with a single output assignment without the square bracket, [], and each output by utilizing the square bracket.

For example,

>> A=magic(3);

>> size(A)

ans = 3 3

>> [m, ~] = size(A)

m = 3

>> [~,n]=size(A)

n = 3

>> [m, n] = size(A)

m = 3

n = 3

Answer 1

[Stephen23]

This is how to do achieve what you asked for:

function [out1,out2,out3,out4,out5,out6,out7] = yourFunction(..)
..
out1 = ..;
..
out7 = ..;
..
if nargout<2
    out1 = [out1,out2,out3,out4,out5,out6,out7];
end
end

[monkeyquant]

You already shared this with me. Appreciate millions!

[Jan]

@monkeyquant: Does this solve your problem? Then please accept it.

Answer 2

[Davide Masiello]

Simply, your function should look like this

function [out1,out2,out3,out4,out5,out6,out6] = yourFunction(input)
...
...
...
out1 = first array;
out2 = second array;
etc.
end

Then, assuming you want your seven arrays outputted by you function be names "a,b,c,d,e,f,g", you call you function this way

[a,b,c,d,e,f,g] = yourFunction(input);

If at some point you want your functoin to return, say, a and f, you call the function this way

[a,~,~,~,~,f,~] = yourFunction(input);

To have the output as a single matrix, all the arrays must have same size. The you can write your function as

function out = yourFunction(input)
...
...
...
out = [first array;second array; third array;..];

end

[monkeyquant]

Thanks, but I hear you what I already knew. Let me rephrase my question: either calling y = function() or function() in the workspace, I would like have either y or ans spits out all list of outputs where the function was defined as [ … ]= function(). The matlab built-in size does that. I just start use MATLAB after 2001 and it spat out the first output in the function for my example above.

[Davide Masiello]

yourFunction

out1 = 1×7

0.7918 0.2587 0.7563 0.7056 0.1305 0.3288 0.4016

out2 = 1×7

0.8575 0.8385 0.1346 0.1032 0.5291 0.0230 0.6765

out3 = 1×7

0.3833 0.4557 0.4541 0.3725 0.8538 0.0923 0.0210

function yourFunction
out1 = rand(1,7)
out2 = rand(1,7)
out3 = rand(1,7)
end

[Stephen23]

"The matlab built-in size does that."

No, it does not, it never has, and it probably never will:

A = rand(4,3,2);
S = size(A) % this is NOT "all of the outputs joined into one array"

S = 1×3

4 3 2

[m,~] = size(A)

m = 4

[~,n] = size(A)

n = 6

[m,n] = size(A)

m = 4

n = 6

SIZE can return an unlimited number of outputs, so your incorrect understanding of how its works is difficult to interpret: should the one "joined" output actually be an infinitely long vector?

[a,b,c,d,e,f,g,h,i,j,k,m,n,o] = size(A)

a = 4

b = 3

c = 2

d = 1

e = 1

f = 1

g = 1

h = 1

i = 1

j = 1

k = 1

m = 1

n = 1

o = 1

Your understanding that the output S is caused by "joining" of all of the outputs is incorrect: the outputs of every function are solely determined from within the function itself. In SIZE's case (and with some other functions ) the outputs change depending on the number of requested outputs (as my example above demonstrates), which you confused with some kind of automagic concatenating of all outputs (but in reality this does not occur).

You need to do this from inside the function (see NARGOUT), not by attempting to use a behavior of MATLAB that does not exist. Or use a comma-separated list into a cell array.

[monkeyquant]

Great to save my time. Just one more thing from what you mentioned of “NARGOUT”. So it is possible by counting the number of outputs or syntax with/without []. I would appreciate if you could direct me to an example.

Answer 3

[Jan]

This works automatically with any function. The ~ simply ignores the replied value in the caller. You do not have to consider this in the function.

If you function replies 7 output, you can request the 3rd and 4th by:

[~, ~, a, b] = YourFunction()

[monkeyquant]

Please see my reply to @DM.