For Loop help for function input

Hello,

I am trying to make a for loop to create inputs for a function, and store outputs - there are 4 inputs, and manually I would type in:

ones(4,1) in the function which is called main, so it looks in the input window as: main(ones(4,1))

This gives 4 outputs, which I would like to store in an excel file later on. However, I want to vary these inputs, and change all 4 of them to make 4^4 combinations (256) with two numbers (1 or 5). So for example:

[1 1 1 1];

[5 1 1 1];

[1 5 1 1];

[5 5 1 1];

[1 1 5 1]; ...................

as you can see, doing this manually is quite tedious - I know a for loop helps here and I can make 256 iterations run by

for i = 1:256

(this is main body)

.....

end

I am confused on whether I should have a nested loop to do this, and how I can store these values in separate rows for each iteration. Any help will be appreciated.

Answer 1

[David Hill]

r=randi(2,5,4);
r(r==2)=5

r = 5×4

1 1 5 5 1 1 5 1 5 1 1 1 1 5 1 5 1 1 5 5

[Pool]

Thanks for the response - so are you saying that using the randi function, I can generate a matrix of all 256 combinations? I think this works if all the possibilties are stated - I guess my follow up question will be on how I should extract the results for each input?

[David Hill]

I am confused when you say 256 combinations. Are there not only 2^4 (16) combinations? I guess I don't understand your question.

R =[ 1     1     1     1
     1     1     1     5
     1     1     5     1
     1     1     5     5
     1     5     1     1
     1     5     1     5
     1     5     5     1
     1     5     5     5
     5     1     1     1
     5     1     1     5
     5     1     5     1
     5     1     5     5
     5     5     1     1
     5     5     1     5
     5     5     5     1
     5     5     5     5];
r=randi(16,4,1)

r = 4×1

7 9 11 15

A=R(r,:)

A = 4×4

1 5 5 1 5 1 1 1 5 1 5 1 5 5 5 1

[Pool]

You are right, sorry for the confusion haha - so if I was running a for loop for i = 1:16 iterations, and I get an output from another function, which gives out a 1x4 vector = [x1 x2 x3 x4] - and I want to store these into an empty matrix (zeros(16,4)), would I write:

for i = 1:16

s = (zeros(16,4));

r=randi(2,16,4);

r(r==2)=5;

x = main(r(i,:));

s(i,:) = x(1,:);

end

For some reason, this does not store the 1x4 outputs for me and gives an error

[David Hill]

s=zeros(16,4);
for i=1:16
    r=randi(2,1,4);%assumed output from another function
    r(r==2)=5;
    s(i,:)=r;
end
s

s = 16×4

1 1 1 5 5 5 5 5 1 1 1 5 1 1 1 5 1 5 1 1 1 5 5 1 5 5 5 5 1 1 5 5 1 1 1 1 5 5 5 1