How to output WHOLE vector in result?

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Scott on 28 Oct 2014
Commented: Steven Lord on 27 Sep 2022
I am trying to build a very simple function which just takes two values from a vector, and reverses their position. So if your inputted vector is [a,b], your output is [b,a].
I realized that there need be no commands in the actual function, we can just switch these values in the function statement itself. So here's what I've got:
function[second,first] = swap(first,second)
This seems to work, however it only outputs one of the values when it returns.
So if I type swap(11,4) It returns only 4, not the whole vector which would be [4,11]
Any thoughts?

Answers (2)

Andrew Reibold
Andrew Reibold on 28 Oct 2014
Edited: Andrew Reibold on 28 Oct 2014
You need to tell Matlab where to store both output arguments or it only gives the first one under the variable 'ans' by default
function [ b, a ] = swap(a, b)
Replicating what you did:
>> swap(4,11)
ans =
ans is only one variable, so only one output will go to it. If you want both outputs, tell Matlab what they should be saved under. Two outputs requires two variables.
Here is an example. Same code, but now I am calling it differently by putting [b,a] first. I am telling Matlab where it can store the outputs
>> [b,a] = swap(4,11)
b =
a =
If you want them to be concatenated into ONE output, it will require at least ONE line of code, or at least to my knowledge it will.
function [ c ] = swap(a, b)
c = [b, a]

James Tursa
James Tursa on 28 Oct 2014
Edited: James Tursa on 28 Oct 2014
Your function, as written, takes two inputs and returns two outputs. You probably called your function with only one output which is why it discarded the second output. It sounds like you want the function to input a vector of 2 elements and return a vector of 2 elements that are swapped. If so, something like this maybe?
function y = swap(x)
y = (insert your element by element swapping code here)
Steven Lord
Steven Lord on 27 Sep 2022
@Ranjith K Since this question doesn't seem to be closely related to the original question from 2014 I recommend you post it as its own question. Use the Ask link at the top of the page.

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