How to initialize an empty vector/null vector in matlab,

I would like to transfer the u_real(n) value to the u_Q1(n) array. But, when I am trying to compile it is telling me that the variable u_Q1 is undefined. How can I define that variable as empty vector.

u_real=real(u);
v_real=real(v);
temp = 0;
for n = 1:100
  if and(u_real(n)>0,v_real(n)>0)
      if n == temp + 1
          u_real(n) == u_Q1(n);
          v_real(n) == v_Q1(n);
          temp = n;
      else
          d = n-temp;
          u_real(n) == u_Q1(n-d+1);
          v_real(n) == v_Q1(n-d+1);
          temp = n-d+1;
      end
  end
end

[James Tursa]

"... transfer the u_real(n) value to the u_Q1(n) array ..."

Looks to me like you are doing the opposite. What is your actual intent?

[Sai]

Ahh..! I'm soo dumb, I just found that.. Sorry but my intention was to transfer the u_real(n) value to a vector. Can you suggest me. Thanks.

Answer 1

[Walter Roberson]

u_Q1 = [];

[Walter Roberson]

u_real(n) == u_Q1(n);

means to compare u_real(n) to u_Q1(n) for equality and have a value of 0 if they are not exactly equal and 1 if they are exactly equal. Then once that logical 0 or 1 is calculated, the result is discarded because the ";" at the end of the line means not to display the value of the expression.

You probably want to use assignment = instead of comparing values ==