Functions Matlab, how to modify?

Hi,

so I have two vectors, Q = (a,l,m) and Z = (d,b,c). I have created a function to calculate Z, but the problem is that I don't want the answear to be d= something1, b=something2 and c= something3. I want it to be Z = =[something1, something2, something3] when I call the function.

function [a,l,m]=test1(d,b,c)
 
a=0;
l=b/sqrt(b^2 + c^2);
m=c/sqrt(d^2 + c^2);
 
a=a*1;
a=a*-1;
l=l*1;
l=l*-1;
m=m*1;
m=m*-1;

Is it possbible to modify the function in some way to achive this?

[Turlough Hughes]

You would write

    function Z = test1(d,b,c)
    % operations to get a,l,m.
    Z=[a l m];
    end

[KALYAN ACHARJYA]

function Z = test1(d,b,c)
a=0;
l=b/sqrt(b^2 + c^2);
m=c/sqrt(d^2 + c^2);
a=a*1;
a=a*-1;
l=l*1;
l=l*-1;
m=m*1;
m=m*-1;
Z=[a l m];
fprintf('Z=[%i %i %i]\n',Z);
end

Answer 1

[Turlough Hughes]

Hi Jenny,

You could write your function to have two outputs as follows:

    function [Z1,Z2] = test1(d,b,c)
    % code to determine a,l,m
    Z1=[a,l,m];
    Z2=[a,-l,-m];
    end

When calling the function you have to specify two outputs if you want them otherwise matlab does not know what to assign the second output to. Basically:

    [Z1,Z2]=test1(d,b,c)

Another thing you could do would be to write a single output where you have 6 elements in a single output variable. That would go something like this:

    function Z = test1(d,b,c)
    % code to get a,l,m
    Z=[a,l,m;a,-l,-m];
    end

When you call the function now you get a single output with six elements that you are looking for.

I recommend looking at onramp tutorials. Especially part 7 on calling functions as well as vectors and matrices, part 3. Though, if you intend to use matlab much you are as well to go through all of the sections.

[Jenny Andersen]

Thank you alot! It seems to be working very well now. One thing that came to mind is that the value differs a bit from be previous expressions, but I gess that is the way functions work.

I will continue with the Onramp course.

Answer 2

[Jenny Andersen]

So I tried Turlough's suggestion again and it seems to be working fine now. But since two vectors will be generated (-d,b,c) and (d,b,-c) I would like to add this information to my code in some way. I have come up with the following, but still I only get one vector.

function [Z] = test1(d,b,c)
a1=0;
l1=b/sqrt(b^2 + c^2);
m1=-c/sqrt(d^2 + c^2);
 
a=0;
l=-b/sqrt(b^2 + c^2);
m=c/sqrt(d^2 + c^2);
 
Z=[a1 l1 m1];
Z=[a l m];
end

[KALYAN ACHARJYA]

Why you have deleted your previous comments, its may confuse to the answer providers? This is answer section, please post your comment in comment section only.