changing the running variable in a "for" loop

I want that the running variable of my for loop changes in the loop. But when I take the next step in the for loop, my made changes for n disappear. In some tutorials was written that I have to use a while loop. But this isn't working as well. Is there an other possibility to solve my problem?

 for n = 1:size(t,2)
        dv = v_0(n+1) - v_0(n);
        while dv ~= 0                                                  
            while dv > 0
                ...
                n = n + dt/delta_t+1;
                break
            end
            while dv < 0
                ...
                break
            end

            break
        end

        ...                                       
continue
end

Answer 1

[Star Strider]

You cannot change the loop index variable within a for loop:

n = n + dt/delta_t+1;

Since ‘n’ is going to increment anyway, avoid confusion and name the assigned variable something else:

nv = n + dt/delta_t+1;

then use it for your calculations.

Answer 2

[Chad Greene]

Yes, I see the problem. It does not make sense to have the for loop variable be the same name as a variable you're defining within the for loop. Perhaps you want something like

 n2 = 0; 
 for n = 1:size(t,2)
           ...
                n2 = n2 + dt/delta_t+1;
 end

Or in some way separate n from n2.

Answer 3

[Pultibus]

Thank you for your answers! Sadly your hints couldn't help me. I did it in another way and my program works now.

Greetings

Pultibus

[Star Strider]

Please post your solution.