MatLab updating a recursive variable.

Question

See the code

x(1) = 0;
k = 1;
   while x(k) <=6
x(k) = x(k) +2
k = k +1;


end

So I want the code to output

x(1) = 2

x(2) = 4

x(3) = 6

Basically I want to write out a list of x(i)s, that gets updated during each iteration. But I am getting an "out of bound" error and I realize that there is a conflict with the way MatLab sees "()" as a vector.

Anyway to get around this?

EDIT1

What if I want to do

x = 0;
y = 0;
k = 1;
   while x <=6 && y<=13
x = x +2;
   y = y + 3 +x;
k = k +1;


end

I want this to output

x = 2

y = 5

x = 4

y = 8

But it's not doing that, and I don't want to do this in two separate scripts. I want to handle everything at once.

Skip trying to label your variable recursively. Just print the step number and the answer for that step. You are already counting what step you are at with $k$. — John Habert, Feb 07 '14 at 07:07
You mean just have $x(k) + 2$ instead of $x(k) = x(k) +2$? I still get errors — Lemon, Feb 07 '14 at 07:10
I'm saying just do $x = x+2$; and for output generate something that looks like: Step #1 : x = 2, Step #2 : x = 4, etc. — John Habert, Feb 07 '14 at 07:12
Huh, interesting. What happens if I want to do this recursively (no more updating), that is x(k+1) = x(k) +2? — Lemon, Feb 07 '14 at 07:17
You would need to define a function and do recursion that way. — John Habert, Feb 07 '14 at 07:20
I just tried out my own method and it kind of works, but I am getting extra information (I actually don't know what they are) — Lemon, Feb 07 '14 at 07:23
Sorry is there a way to do this with more than one variable? — Lemon, Feb 07 '14 at 08:00

score 0 · Accepted Answer · answered Feb 07 '14 at 07:29

0

There's an error in your code, in the line

x(k)=x(k) + 2

because x(k) is not yet defined. See the correct code:

x(1) = 0;
k = 1;
   while x(k) <=6

   x(k+1) = x(k) +2

    k = k +1;

end

answered Feb 07 '14 at 07:29

5xum

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What if I want to update two variables at once? – Lemon Feb 07 '14 at 08:13
Provide an example. – 5xum Feb 07 '14 at 08:13
See edit post please – Lemon Feb 07 '14 at 08:15

MatLab updating a recursive variable.

1 Answers1