simulink matlab function code error?

hello every one , i have been tring to implement calculating twiddle factors in matlab editor using "function", my code is working fine , the same thing i am implementing in the matlab function block in simulink its not working please kindly help, my code in matlab function block is

    function y = twiddles_12345(u)

    fft_length = input('u');

    for mm = 0:1:(fft_length-1)
    theta = (-2*pi*mm*1/fft_length);

    twiddle(mm+1) = cos(theta) + (1i*(sin(theta)));

    y = real(twiddle);
    y = y'
 end

Answer 1

[Walter Roberson]

Before the loop use

twiddle = complex(zeros(1,fft_length), zeros(1,fft_length));

In the loop you might need

      twiddle(mm+1) = complex(cos(theta), sin(theta));

[Sandeep Kumar]

sir, i have made the necessary changes which u said, but still it is showing some errors? it is working in matlab editor, but not in matlab function of simulink???

    function y = twiddles_123(u)

    fft_length = input('u');

    twiddle = complex(zeros(1,fft_length), zeros(1,fft_length));

   for mm = 0:1:(fft_length-1)
    theta = (-2*pi*mm*1/fft_length);

    twiddle(mm+1) = cos(theta) + (1i*(sin(theta)));
    twiddle(mm+1) = complex(cos(theta), sin(theta));
    y = real(twiddle);
    y = y'
    end

[Walter Roberson]

What errors is it showing?

[Walter Roberson]

The

   y = real(twiddle);
   y = y'

should not be inside the loop.